diff --git a/src/component/visualMap/PiecewiseModel.js b/src/component/visualMap/PiecewiseModel.js
index df03ed051a..d3ca83db87 100644
--- a/src/component/visualMap/PiecewiseModel.js
+++ b/src/component/visualMap/PiecewiseModel.js
@@ -402,7 +402,7 @@ var resetMethods = {
 
         if (thisOption.minOpen) {
             pieceList.push({
-                index: index++,
+                index: index,
                 interval: [-Infinity, dataExtent[0]],
                 close: [0, 0]
             });