diff --git a/dpdata/plugins/deepmd.py b/dpdata/plugins/deepmd.py
index 51fd4667a..26cdc3824 100644
--- a/dpdata/plugins/deepmd.py
+++ b/dpdata/plugins/deepmd.py
@@ -95,7 +95,9 @@ def from_system_mix(self, file_name, type_map=None, **kwargs):
             file_name, type_map=type_map, labels=False
         )
 
-    def to_system(self, data, file_name, prec=np.float64, **kwargs):
+    def to_system(
+        self, data, file_name, set_size: int = 2000, prec=np.float64, **kwargs
+    ):
         """Dump the system in deepmd mixed type format (numpy binary) to `folder`.
 
         The frames were already split to different systems, so these frames can be dumped to one single subfolders
@@ -107,12 +109,14 @@ def to_system(self, data, file_name, prec=np.float64, **kwargs):
             System data
         file_name : str
             The output folder
+        set_size : int, default=2000
+            set size
         prec : {numpy.float32, numpy.float64}
             The floating point precision of the compressed data
         **kwargs : dict
             other parameters
         """
-        dpdata.deepmd.mixed.dump(file_name, data, comp_prec=prec)
+        dpdata.deepmd.mixed.dump(file_name, data, set_size=set_size, comp_prec=prec)
 
     def from_labeled_system_mix(self, file_name, type_map=None, **kwargs):
         return dpdata.deepmd.mixed.to_system_data(
diff --git a/tests/test_deepmd_mixed.py b/tests/test_deepmd_mixed.py
index 6311410ef..7e522e065 100644
--- a/tests/test_deepmd_mixed.py
+++ b/tests/test_deepmd_mixed.py
@@ -109,6 +109,107 @@ def test_str(self):
         )
 
 
+class TestMixedMultiSystemsDumpLoadSetSize(
+    unittest.TestCase, CompLabeledSys, MultiSystems, IsNoPBC
+):
+    def setUp(self):
+        self.places = 6
+        self.e_places = 6
+        self.f_places = 6
+        self.v_places = 6
+
+        # C1H4
+        system_1 = dpdata.LabeledSystem(
+            "gaussian/methane.gaussianlog", fmt="gaussian/log"
+        )
+
+        # C1H3
+        system_2 = dpdata.LabeledSystem(
+            "gaussian/methane_sub.gaussianlog", fmt="gaussian/log"
+        )
+
+        tmp_data = system_1.data.copy()
+        tmp_data["atom_numbs"] = [1, 1, 1, 2]
+        tmp_data["atom_names"] = ["C", "H", "A", "B"]
+        tmp_data["atom_types"] = np.array([0, 1, 2, 3, 3])
+        # C1H1A1B2
+        system_1_modified_type_1 = dpdata.LabeledSystem(data=tmp_data)
+
+        tmp_data = system_1.data.copy()
+        tmp_data["atom_numbs"] = [1, 1, 2, 1]
+        tmp_data["atom_names"] = ["C", "H", "A", "B"]
+        tmp_data["atom_types"] = np.array([0, 1, 2, 2, 3])
+        # C1H1A2B1
+        system_1_modified_type_2 = dpdata.LabeledSystem(data=tmp_data)
+
+        tmp_data = system_1.data.copy()
+        tmp_data["atom_numbs"] = [1, 1, 1, 2]
+        tmp_data["atom_names"] = ["C", "H", "A", "D"]
+        tmp_data["atom_types"] = np.array([0, 1, 2, 3, 3])
+        # C1H1A1C2
+        system_1_modified_type_3 = dpdata.LabeledSystem(data=tmp_data)
+
+        self.ms = dpdata.MultiSystems(
+            system_1,
+            system_2,
+            system_1_modified_type_1,
+            system_1_modified_type_2,
+            system_1_modified_type_3,
+        )
+        self.ms.to_deepmd_npy_mixed("tmp.deepmd.mixed", set_size=1)
+        self.place_holder_ms = dpdata.MultiSystems()
+        self.place_holder_ms.from_deepmd_npy("tmp.deepmd.mixed", fmt="deepmd/npy")
+        self.systems = dpdata.MultiSystems()
+        self.systems.from_deepmd_npy_mixed("tmp.deepmd.mixed", fmt="deepmd/npy/mixed")
+        self.system_1 = self.ms["C1H4A0B0D0"]
+        self.system_2 = self.systems["C1H4A0B0D0"]
+        mixed_sets = glob("tmp.deepmd.mixed/*/set.*")
+        self.assertEqual(len(mixed_sets), 5)
+        for i in mixed_sets:
+            self.assertEqual(
+                os.path.exists(os.path.join(i, "real_atom_types.npy")), True
+            )
+
+        self.system_names = [
+            "C1H4A0B0D0",
+            "C1H3A0B0D0",
+            "C1H1A1B2D0",
+            "C1H1A2B1D0",
+            "C1H1A1B0D2",
+        ]
+        self.system_sizes = {
+            "C1H4A0B0D0": 1,
+            "C1H3A0B0D0": 1,
+            "C1H1A1B2D0": 1,
+            "C1H1A2B1D0": 1,
+            "C1H1A1B0D2": 1,
+        }
+        self.atom_names = ["C", "H", "A", "B", "D"]
+
+    def tearDown(self):
+        if os.path.exists("tmp.deepmd.mixed"):
+            shutil.rmtree("tmp.deepmd.mixed")
+
+    def test_len(self):
+        self.assertEqual(len(self.ms), 5)
+        self.assertEqual(len(self.place_holder_ms), 2)
+        self.assertEqual(len(self.systems), 5)
+
+    def test_get_nframes(self):
+        self.assertEqual(self.ms.get_nframes(), 5)
+        self.assertEqual(self.place_holder_ms.get_nframes(), 5)
+        self.assertEqual(self.systems.get_nframes(), 5)
+
+    def test_str(self):
+        self.assertEqual(str(self.ms), "MultiSystems (5 systems containing 5 frames)")
+        self.assertEqual(
+            str(self.place_holder_ms), "MultiSystems (2 systems containing 5 frames)"
+        )
+        self.assertEqual(
+            str(self.systems), "MultiSystems (5 systems containing 5 frames)"
+        )
+
+
 class TestMixedMultiSystemsTypeChange(
     unittest.TestCase, CompLabeledSys, MultiSystems, IsNoPBC
 ):