diff --git a/src/chart/tree/TreeSeries.js b/src/chart/tree/TreeSeries.js
index 8dece1fd6493272b757ff454a9be0f117ee51471..7dda0f6b7deedcaf1be361f5ab79e0e63c2d9d72 100644
--- a/src/chart/tree/TreeSeries.js
+++ b/src/chart/tree/TreeSeries.js
@@ -133,7 +133,7 @@ export default SeriesModel.extend({
         // the layout of the tree, two value can be selected, 'orthogonal' or 'radial'
         layout: 'orthogonal',
 
-        roam: false,
+        roam: false, // true | false | 'move' | 'scale', see module:component/helper/RoamController.
         // Symbol size scale ratio in roam
         nodeScaleRatio: 0.4,
 
diff --git a/test/tree-roam.html b/test/tree-roam.html
index fac8df44bf5d401777c09c7ade9a95df546c706f..8450f58c204509e470ab6ddec2cc77e94e81c1f2 100644
--- a/test/tree-roam.html
+++ b/test/tree-roam.html
@@ -69,6 +69,8 @@ under the License.
                                     bottom: '14%',
 
                                     roam: true,
+                                    // roam: 'scale',
+                                    // roam: 'move',
 
                                     layout: 'radial',