tickLength: Number

Sets the length of Tick Marks that are drawn for axisY striplines’s label when labels are placed outside.

var  chart =  new  CanvasJS.Chart("container", {
 .
 .
 axisY:{
	stripLines: [
		{
		 tickLength: 5
		}
	]
   },
 .
 . 
});
chart.render();