diff --git a/doc/conf.py b/doc/conf.py
index 824503f8b6..71488ac4e0 100644
--- a/doc/conf.py
+++ b/doc/conf.py
@@ -28,7 +28,7 @@ def mkindex(dirname):
     
     newfindex = open(dirname + "index.md", "a")
     for root, dirs, files in os.walk(dirname, topdown=False):
-        newnames = [name for name in files if name != "index.md" and name not in oldnames]
+        newnames = [name for name in files if "index.md" not in name and name not in oldnames]
         for name in newnames:
             f = open(dirname + name, "r")
             _lines = f.readlines()
@@ -45,6 +45,62 @@ def mkindex(dirname):
     
     newfindex.close()
 
+def classify_index_TS():
+    dirname = "troubleshooting/"
+    oldfindex = open(dirname + "index.md", "r")
+    oldlist = oldfindex.readlines()
+    oldfindex.close()
+
+    oldnames = []
+    sub_titles = []
+    heads = []
+    while(len(oldlist) > 0):
+        entry = oldlist.pop(0)
+        if (entry.find("(") >= 0):
+            _name = entry[entry.find("(")+1 : entry.find(")")]
+            oldnames.append(_name)
+            continue
+        if (entry.find("##") >= 0):
+            _name = entry[entry.find("##")+3:-1]
+            sub_titles.append(_name)
+            continue
+        entry.strip()
+        if (entry != '\n'):
+            heads.append(entry)
+    
+    newfindex = open(dirname + "index.md", "w")
+    for entry in heads:
+        newfindex.write(entry)
+    newfindex.write('\n')
+    sub_lists = [[],[]]
+    for root, dirs, files in os.walk(dirname, topdown=False):
+        newnames = [name for name in files if "index.md" not in name]
+        for name in newnames:
+            f = open(dirname + name, "r")
+            _lines = f.readlines()
+            f.close()
+            for _headline in _lines:
+                _headline = _headline.strip("#")
+                headline = _headline.strip()
+                if (len(headline) == 0 or headline[0] == "." or headline[0] == "="):
+                    continue
+                else:
+                    break
+            longname = "- ["+headline+"]"+"("+name+")\n"
+            if ("howtoset_" in name):
+                sub_lists[1].append(longname)
+            else:
+                sub_lists[0].append(longname)
+    
+    newfindex.write("## Trouble shooting\n")
+    for entry in sub_lists[0]:
+        newfindex.write(entry)
+    newfindex.write("\n")
+    newfindex.write("## Parameters setting\n")
+    for entry in sub_lists[1]:
+        newfindex.write(entry)
+    newfindex.close()
+
 
 # -- Project information -----------------------------------------------------
 
@@ -68,6 +124,7 @@ def mkindex(dirname):
 
 mkindex("troubleshooting")
 mkindex("development")
+classify_index_TS()
 
 extensions = [
     "sphinx_rtd_theme",
diff --git a/doc/troubleshooting/howtoset_netsize.md b/doc/troubleshooting/howtoset_netsize.md
new file mode 100644
index 0000000000..800abb9a08
--- /dev/null
+++ b/doc/troubleshooting/howtoset_netsize.md
@@ -0,0 +1,141 @@
+# How to tune Fitting/embedding-net size ?
+
+Here are some test forms on fitting-net size tuning or embedding-net size tuning performed on several different systems.
+
+
+## Al2O3
+
+### Fitting net size tuning form on Al2O3: (embedding-net size: [25,50,100])
+
+Fitting-net size | Energy L2err(eV) | Energy L2err/Natoms(eV) | Force L2err(eV/Angstrom)
+---|---|---|---
+[240,240,240] |   1.742252e-02 |  7.259383e-05 |  4.014115e-02 
+[80,80,80]    |   1.799349e-02 |  7.497287e-05 |  4.042977e-02 
+[40,40,40]    |   1.799036e-02 |  7.495984e-05 |  4.068806e-02 
+[20,20,20]    |   1.834032e-02 |  7.641801e-05 |  4.094784e-02 
+[10,10,10]    |   1.913058e-02 |  7.971073e-05 |  4.154775e-02 
+[5,5,5]       |   1.932914e-02 |  8.053808e-05 |  4.188052e-02 
+[4,4,4]       |   1.944832e-02 |  8.103467e-05 |  4.217826e-02 
+[3,3,3]       |   2.068631e-02 |  8.619296e-05 |  4.300497e-02 
+[2,2,2]       |   2.267962e-02 |  9.449840e-05 |  4.413609e-02 
+[1,1,1]       |   2.813596e-02 |  1.172332e-04 |  4.781115e-02 
+[]            |   3.135002e-02 |  1.306251e-04 |  5.373120e-02 
+
+_[] means no hidden layer, but there is still a linear output layer. This situation is equal to the linear regression._
+
+### Embedding net size tuning form on Al2O3: (Fitting-net size: [240,240,240])
+
+Embedding-net size | Energy L2err(eV) | Energy L2err/Natoms(eV) | Force L2err(eV/Angstrom)
+---|---|---|---
+[25,50,100]  | 1.742252e-02  | 7.259383e-05  | 4.014115e-02  
+[10,20,40]   | 2.909990e-02  | 1.212496e-04  | 4.734667e-02  
+[5,10,20]    | 3.357767e-02  | 1.399070e-04  | 5.706385e-02  
+[4,8,16]     | 6.060367e-02  | 2.525153e-04  | 7.333304e-02  
+[3,6,12]     | 5.656043e-02  | 2.356685e-04  | 7.793539e-02  
+[2,4,8]      | 5.277023e-02  | 2.198759e-04  | 7.459995e-02  
+[1,2,4]      | 1.302282e-01  | 5.426174e-04  | 9.672238e-02  
+
+
+## Cu
+
+### Fitting net size tuning form on Cu: (embedding-net size: [25,50,100])
+
+Fitting-net size | Energy L2err(eV) | Energy L2err/Natoms(eV) | Force L2err(eV/Angstrom)
+---|---|---|---
+[240,240,240]  | 4.135548e-02   |  1.615449e-04   |  8.940946e-02
+[20,20,20]     | 4.323858e-02   |  1.689007e-04   |  8.955762e-02 
+[10,10,10]     | 4.399364e-02   |  1.718502e-04   |  8.962891e-02 
+[5,5,5]        | 4.468404e-02   |  1.745470e-04   |  8.970111e-02 
+[4,4,4]        | 4.463580e-02   |  1.743586e-04   |  8.972011e-02 
+[3,3,3]        | 4.493758e-02   |  1.755374e-04   |  8.971303e-02 
+[2,2,2]        | 4.500736e-02   |  1.758100e-04   |  8.973878e-02 
+[1,1,1]        | 4.542073e-02   |  1.774247e-04   |  8.964761e-02 
+[]             | 4.545168e-02   |  1.775456e-04   |  8.983201e-02 
+
+### Embedding net size tuning form on Cu: (Fitting-net size: [240,240,240])
+
+Embedding-net size | Energy L2err(eV) | Energy L2err/Natoms(eV) | Force L2err(eV/Angstrom)
+---|---|---|---
+[25,50,100]          | 4.135548e-02  |  1.615449e-04  |  8.940946e-02  
+[20,40,80]           | 4.203562e-02  |  1.642016e-04  |  8.925881e-02  
+[15,30,60]           | 4.146672e-02  |  1.619794e-04  |  8.936911e-02  
+[10,20,40]           | 4.263060e-02  |  1.665258e-04  |  8.955818e-02  
+[5,10,20]            | 4.994913e-02  |  1.951138e-04  |  9.007786e-02   
+[4,8,16]             | 1.022157e-01  |  3.992802e-04  |  9.532119e-02   
+[3,9,12]             | 1.362098e-01  |  5.320695e-04  |  1.073860e-01   
+[2,4,8]              | 7.061800e-02  |  2.758515e-04  |  9.126418e-02   
+[1,2,4] && seed = 1  | 9.843161e-02  |  3.844985e-04  |  9.348505e-02   
+[1,2,4] && seed = 2  | 9.404335e-02  |  3.673568e-04  |  9.304089e-02   
+[1,2,4] && seed = 3  | 1.508016e-01  |  5.890688e-04  |  1.382356e-01   
+[1,2,4] && seed = 4  | 9.686949e-02  |  3.783965e-04  |  9.294820e-02   
+
+
+## Water
+
+### Fitting net size tuning form on water: (embedding-net size: [25,50,100])
+
+Fitting-net size | Energy L2err/Natoms(eV) | Force L2err(eV/Angstrom)
+---|---|---
+[240,240,240]  | 9.1589E-04  | 5.1540E-02
+[200,200,200]  | 9.3221E-04  | 5.2366E-02
+[160,160,160]  | 9.4274E-04  | 5.3403E-02
+[120,120,120]  | 9.5407E-04  | 5.3093E-02
+[80,80,80]     | 9.4605E-04  | 5.3402E-02
+[40,40,40]     | 9.8533E-04  | 5.5790E-02
+[20,20,20]     | 1.0057E-03  | 5.8232E-02
+[10,10,10]     | 1.0466E-03  | 6.2279E-02
+[5,5,5]        | 1.1154E-03  | 6.7994E-02
+[4,4,4]        | 1.1289E-03  | 6.9613E-02
+[3,3,3]        | 1.2368E-03  | 7.9786E-02
+[2,2,2]        | 1.3558E-03  | 9.7042E-02
+[1,1,1]        | 1.4633E-03  | 1.1265E-01
+[]             | 1.5193E-03  | 1.2136E-01
+
+### Embedding net size tuning form on water: (Fitting-net size: [240,240,240])
+
+Embedding-net size | Energy L2err/Natoms(eV) | Force L2err(eV/Angstrom)
+---|---|---
+[25,50,100]  | 9.1589E-04  | 5.1540E-02
+[20,40,80]   | 9.5080E-04  | 5.3593E-02
+[15,30,60]   | 9.7996E-04  | 5.6338E-02
+[10,20,40]   | 1.0353E-03  | 6.2776E-02
+[5,10,20]    | 1.1254E-03  | 7.3195E-02
+[4,8,16]     | 1.2495E-03  | 8.0371E-02
+[3,6,12]     | 1.3604E-03  | 9.9883E-02
+[2,4,8]      | 1.4358E-03  | 9.7389E-02
+[1,2,4]      | 2.1765E-03  | 1.7276E-01
+
+
+## Mg-Al
+
+### Fitting net size tuning form on Mg-Al: (embedding-net size: [25,50,100])
+
+Fitting-net size | Energy L2err/Natoms(eV) | Force L2err(eV/Angstrom)
+---|---|---
+[240,240,240]  | 3.9606e-03  | 1.6289e-02
+[200,200,200]  | 3.9449e-03  | 1.6471e-02
+[160,160,160]  | 4.0947e-03  | 1.6413e-02
+[120,120,120]  | 3.9234e-03  | 1.6283e-02
+[80,80,80]     | 3.9758e-03  | 1.6506e-02
+[40,40,40]     | 3.9142e-03  | 1.6348e-02
+[20,20,20]     | 4.1302e-03  | 1.7006e-02
+[10,10,10]     | 4.3433e-03  | 1.7524e-02
+[5,5,5]        | 5.3154e-03  | 1.9716e-02
+[4,4,4]        | 5.4210e-03  | 1.9710e-02
+[2,2,2]        | 6.2667e-03  | 2.2568e-02
+[1,1,1]        | 7.3676e-03  | 2.6375e-02
+[]             | 7.3999e-03  | 2.6097e-02
+
+### Embedding net size tuning form on Mg-Al: (Fitting-net size: [240,240,240])
+
+Embedding-net size | Energy L2err/Natoms(eV) | Force L2err(eV/Angstrom)
+---|---|---
+[25,50,100]  | 3.9606e-03  | 1.6289e-02
+[20,40,80]   | 4.0292e-03  | 1.6555e-02
+[15,30,60]   | 4.1743e-03  | 1.7026e-02
+[10,20,40]   | 4.8138e-03  | 1.8516e-02
+[5,10,20]    | 5.6052e-03  | 2.0709e-02
+[4,8,16]     | 6.1335e-03  | 2.1450e-02
+[3,6,12]     | 6.6469e-03  | 2.3003e-02
+[2,4,8]      | 6.8222e-03  | 2.6318e-02
+[1,2,4]      | 1.0678e-02  | 3.9559e-02
diff --git a/doc/troubleshooting/howtoset_num_nodes.md b/doc/troubleshooting/howtoset_num_nodes.md
new file mode 100644
index 0000000000..131732ea42
--- /dev/null
+++ b/doc/troubleshooting/howtoset_num_nodes.md
@@ -0,0 +1,16 @@
+# How to control the number of nodes used by a job ?
+
+Set the number of CPU nodes used by DP algorithms with:
+```bash
+mpirun -np $num_nodes dp
+```
+Set the number of threads used by DP algorithms with:
+```bash
+export OMP_NUM_THREADS=$num_threads
+```
+
+Set the number of CPU nodes used by TF kernels with:
+```bash
+export TF_INTRA_OP_PARALLELISM_THREADS=$num_nodes
+export TF_INTER_OP_PARALLELISM_THREADS=$num_nodes
+```
diff --git a/doc/troubleshooting/howtoset_rcut.md b/doc/troubleshooting/howtoset_rcut.md
new file mode 100644
index 0000000000..f8ba56ccaa
--- /dev/null
+++ b/doc/troubleshooting/howtoset_rcut.md
@@ -0,0 +1,7 @@
+# Do we need to set rcut < half boxsize ?
+
+When seeking the neighbors of atom i under periodic boundary condition, deepmd-kit considers all j atoms within cutoff rcut from atom i in all mirror cells.
+
+So, so there is no limitation on the setting of rcut.
+
+PS: The reason why some softwares require rcut < half boxsize is that they only consider the nearest mirrors from the center cell. Deepmd-kit is totally different from them.
diff --git a/doc/troubleshooting/howtoset_sel.md b/doc/troubleshooting/howtoset_sel.md
new file mode 100644
index 0000000000..915fdd3094
--- /dev/null
+++ b/doc/troubleshooting/howtoset_sel.md
@@ -0,0 +1,11 @@
+# How to set sel ?
+
+`sel` is short for "selected number of atoms in `rcut`".
+
+`sel_a[i]` is a list of integers. The length of the list should be the same as the number of atom types in the system. 
+
+`sel_a[i]` gives the number of selected number of type `i` neighbors within `rcut`. To ensure that the results are strictly accurate, `sel_a[i]` should be larger than the largest number of type `i` neighbors in the `rcut`.
+
+However, the computation overhead increases with `sel_a[i]`, therefore, `sel_a[i]` should be as small as possible.
+
+The setting of `sel_a[i]` should balance the above two considerations.
diff --git a/doc/troubleshooting/index.md b/doc/troubleshooting/index.md
index 0db7b82198..1c7d642355 100644
--- a/doc/troubleshooting/index.md
+++ b/doc/troubleshooting/index.md
@@ -1,10 +1,16 @@
-# Troubleshooting
+# FAQs
 In consequence of various differences of computers or systems, problems may occur. Some common circumstances are listed as follows. 
+In addition, some frequently asked questions about parameters setting are listed as follows.
 If other unexpected problems occur, you're welcome to contact us for help.
-   
 
+## Trouble shooting
 - [Installation](installation.md)
 - [The temperature undulates violently during early stages of MD](md-energy-undulation.md)
 - [MD: cannot run LAMMPS after installing a new version of DeePMD-kit](md-version-compatibility.md)
 - [Model compatability](model-compatability.md)
-- [Do we need to set rcut < half boxsize ?](rcut.md)
+
+## Parameters setting
+- [How to tune Fitting/embedding-net size ?](howtoset_netsize.md)
+- [How to control the number of nodes used by a job ?](howtoset_num_nodes.md)
+- [Do we need to set rcut < half boxsize ?](howtoset_rcut.md)
+- [How to set sel ?](howtoset_sel.md)
diff --git a/doc/troubleshooting/rcut.md b/doc/troubleshooting/rcut.md
deleted file mode 100644
index 74aafe72e1..0000000000
--- a/doc/troubleshooting/rcut.md
+++ /dev/null
@@ -1,7 +0,0 @@
-# Do we need to set rcut < half boxsize ?
-
-When seeking the neighbors of atom i under periodic boundary condition, deepmd-kit considers all j atoms within cutoff R<sub>cut</sub> from atom i in all mirror cells.
-
-So there is no limitation on the setting of R<sub>cut</sub>.
-
-PS: The reason why some softwares require R<sub>cut</sub> < half boxsize is that they only consider the nearest mirrors from the center cell. Deepmd-kit is totally different from them.