Right-click on the axis and select Axis Settings. Notice the Reference Line area in the lower right corner of the dialog. You can add as many lines as you want. Each one is plotted at a given value, label (optional), color, opacity, and line style. Remember to click Add for each definition. Right-click on the axis again when you have the desired result and select Save to Column Property. The Axis column property will assure that this data column will always be plotted this way from now on.
thanks @markbailey for replying. I gain new knowledge for using the features. But now i want use script to script out the line and label the line into the chart. I have try lot of times to add and label line, but it still cannot successful.