diff --git a/src/tool/color.ts b/src/tool/color.ts
index bedbd71fa..bacf1fa9e 100644
--- a/src/tool/color.ts
+++ b/src/tool/color.ts
@@ -233,15 +233,15 @@ export function parse(colorStr: string, rgbaArr?: number[]): number[] {
                         ? setRgba(rgbaArr, +params[0], +params[1], +params[2], 1)
                         : setRgba(rgbaArr, 0, 0, 0, 1);
                 }
-                alpha = parseCssFloat(params.pop() as string); // jshint ignore:line
+                alpha = parseCssFloat(params.pop()); // jshint ignore:line
             // Fall through.
             case 'rgb':
-                if (params.length === 3 || params.length === 4) {
+                if (params.length >= 3) {
                     setRgba(rgbaArr,
                         parseCssInt(params[0]),
                         parseCssInt(params[1]),
                         parseCssInt(params[2]),
-                        alpha
+                        params.length === 3 ? alpha : parseCssFloat(params[3])
                     );
                     putToCache(colorStr, rgbaArr);
                     return rgbaArr;
@@ -255,7 +255,7 @@ export function parse(colorStr: string, rgbaArr?: number[]): number[] {
                     setRgba(rgbaArr, 0, 0, 0, 1);
                     return;
                 }
-                params[3] = parseCssFloat(params[3] as string);
+                params[3] = parseCssFloat(params[3]);
                 hsla2rgba(params, rgbaArr);
                 putToCache(colorStr, rgbaArr);
                 return rgbaArr;
diff --git a/test/ut/spec/tool/color.test.ts b/test/ut/spec/tool/color.test.ts
index 5b4423f56..9a5fe37c4 100644
--- a/test/ut/spec/tool/color.test.ts
+++ b/test/ut/spec/tool/color.test.ts
@@ -7,9 +7,14 @@ describe('colorTool', function () {
 		['rgba(17, 163, 69, 0.5)', [17, 163, 69, 0.5]],
 		['rgb(17, 163, 69)', [17, 163, 69, 1]],
 		['rgb(2, 163, 254, 1)', [2, 163, 254, 1]],
+		['rgb(2, 163, 254, 0.8)', [2, 163, 254, 0.8]],
+		['rgb(2, 163, 254, 20%)', [2, 163, 254, 0.2]],
+		['rgba(2, 163, 254, 50%)', [2, 163, 254, 0.5]],
 		['#14c4ba00', [20, 196, 186, 0]],
+		['#14c4bacc', [20, 196, 186, 0.8]],
 		['#14c4ba', [20, 196, 186, 1]],
 		['#07f0', [0, 119, 255, 0]],
+		['#07fc', [0, 119, 255, 0.8]],
 		['#07f', [0, 119, 255, 1]],
 		['red', [255, 0, 0, 1]],
 		['blue', [0, 0, 255, 1]]