How to hide the clip boundary line for reference drawing in printout drawing?

Thats the view attributes dialog. You need to find the print attributes dialog which you will find on the print dialog.

You’ll need to provide some screenshots of your print attributes dialog

Thank you.

This case does not work.

Personally I clip references using a shape, and the shape is drawn on a level set not to plot. Otherwise I think there is a setting in print attributes called Boundary Display which, if turned off, will stop the ref clip boundary from printing.