@kly_tianjin,
To distinguish which dataSeries is attached to the corresponding axis you can set the color of axis according to the dataSeries or you can use legend text as shown in this documentation page. You can also use legend to hide/unhide dataSeries in case of multiseries chart using itemclick property. Please take a look at this documentation page for more information hiding / unhiding dataseries.
___________
Indranil Deo
Team CanvasJS