diff --git a/src/model/mixin/lineStyle.js b/src/model/mixin/lineStyle.js
index 868e7d82c3405af8c078113a528e455fc8cb6bcd..188987555421708c4ad753031235fafb0683f5ea 100644
--- a/src/model/mixin/lineStyle.js
+++ b/src/model/mixin/lineStyle.js
@@ -34,8 +34,9 @@ var getLineStyle = makeStyleMapper(
 export default {
     getLineStyle: function (excludes) {
         var style = getLineStyle(this, excludes);
-        var lineDash = this.getLineDash(style.lineWidth);
-        lineDash && (style.lineDash = lineDash);
+        // Always set lineDash whether dashed, otherwise we can not 
+        // erase the previous style when assigning to el.style.
+        style.lineDash = this.getLineDash(style.lineWidth);
         return style;
     },
 
@@ -46,7 +47,15 @@ export default {
         var lineType = this.get('type');
         var dotSize = Math.max(lineWidth, 2);
         var dashSize = lineWidth * 4;
-        return (lineType === 'solid' || lineType == null) ? null
-            : (lineType === 'dashed' ? [dashSize, dashSize] : [dotSize, dotSize]);
+        return (lineType === 'solid' || lineType == null) 
+            // Use `false` but not `null` for the solid line here, because `null` might be 
+            // ignored when assigning to `el.style`. e.g., when setting `lineStyle.type` as 
+            // `'dashed'` and `emphasis.lineStyle.type` as `'solid'` in graph series, the 
+            // `lineDash` gotten form the latter one is not able to erase that from the former 
+            // one if using `null` here according to the emhpsis strategy in `util/graphic.js`.
+            ? false
+            : lineType === 'dashed' 
+            ? [dashSize, dashSize] 
+            : [dotSize, dotSize];
     }
 };
\ No newline at end of file
diff --git a/test/hoverStyle.html b/test/hoverStyle.html
index 993ed69bf5a8566046a069cd0697752f1c04d74d..e3f80dc22f979b8b7d527fac41196931c1151630 100644
--- a/test/hoverStyle.html
+++ b/test/hoverStyle.html
@@ -57,6 +57,7 @@ under the License.
         <div id="mainb1"></div>
         <div id="mainb2"></div>
         <div id="mainb3"></div>
+        <div id="mainb4"></div>
 
         <div id="main0"></div>
         <div id="main1"></div>
@@ -328,6 +329,56 @@ under the License.
 
 
 
+
+
+        <script>
+            require(['echarts'], function (echarts) {
+                var option = {
+                    hoverLayerThreshold: hoverLayerThreshold,
+                    series: [{
+                        type: 'graph',
+                        symbolSize: 20,
+                        focusNodeAdjacency: true,
+                        data: [
+                            {value: 100, name: 'aa', x: 100, y: 200},
+                            {value: 150, name: 'bb', x: 450, y: 300},
+                            {value: 200, name: 'cc', x: 200, y: 100},
+                            {value: 250, name: 'dd', x: 450, y: 250}
+                        ],
+                        links: [
+                            {source: 'aa', target: 'bb'},
+                            {source: 'aa', target: 'dd'},
+                            {source: 'cc', target: 'bb'}
+                        ],
+                        lineStyle: {
+                            color: 'green',
+                            type: 'dashed', // [4, 6],
+                            width: 3
+                        },
+                        emphasis: {
+                            lineStyle: {
+                                color: 'orange',
+                                type: 'solid',
+                                width: 8
+                                // opacity: .8
+                            }
+                        }
+                    }]
+                };
+
+                var chart = testHelper.create(echarts, 'mainb4', {
+                    title: [
+                        'normal line is **green dashed width 3**,', 
+                        'should become **orange solid width 8** when hovered'
+                    ],
+                    option: option,
+                    height: 200
+                });
+            });
+        </script>
+
+
+
         <script>
             require(['echarts'], function (echarts) {
                 var option = {