diff --git a/src/chart/graph/circularLayoutHelper.js b/src/chart/graph/circularLayoutHelper.js
index 93f888ad8c..f6979b7193 100644
--- a/src/chart/graph/circularLayoutHelper.js
+++ b/src/chart/graph/circularLayoutHelper.js
@@ -77,8 +77,8 @@ export function circularLayout(seriesModel, basedOn) {
 
     graph.eachEdge(function (edge, index) {
         var curveness = zrUtil.retrieve3(
+            edge.getModel().get('lineStyle.curveness') || null,
             getCurvenessForEdge(edge, seriesModel, index),
-            edge.getModel().get('lineStyle.curveness'),
             0
         );
         var p1 = vec2.clone(edge.node1.getLayout());
diff --git a/src/chart/helper/multipleGraphEdgeHelper.js b/src/chart/helper/multipleGraphEdgeHelper.js
index e7aaf46710..5a5810b8c0 100644
--- a/src/chart/helper/multipleGraphEdgeHelper.js
+++ b/src/chart/helper/multipleGraphEdgeHelper.js
@@ -17,6 +17,8 @@
 * under the License.
 */
 
+import * as zrUtil from 'zrender/src/core/util';
+
 var KEY_DELIMITER = '-->';
 /**
  * params handler
@@ -42,7 +44,7 @@ var createCurveness = function (seriesModel, appendLength) {
     if (typeof autoCurvenessParmas === 'number') {
         length = autoCurvenessParmas;
     }
-    else if (Object.prototype.toString.call(autoCurvenessParmas) === '[object Array]') {
+    else if (zrUtil.isArray(autoCurvenessParmas)) {
         seriesModel._curvenessList = autoCurvenessParmas;
         return;
     }
@@ -178,7 +180,7 @@ export function createEdgeMapForCurveness(n1, n2, seriesModel, dataIndex) {
  */
 export function getCurvenessForEdge(edge, seriesModel, index, needReverse) {
     const autoCurvenessParams = getAutoCurvenessParams(seriesModel);
-    const isArrayParam = Object.prototype.toString.call(autoCurvenessParams) === '[object Array]';
+    const isArrayParam = zrUtil.isArray(autoCurvenessParams);
     if (!autoCurvenessParams) {
         return null;
     }