Provided is a method for verifying a pattern of a semiconductor device. In the method, a designed layout of target patterns is provided, and transferring the designed layout on a wafer to form wafer patterns. Wafer patterns image contour is obtain. The image contour for wafer patterns on the designed layout are matched, After edge differences between the designed layout and the wafer patterns image contour are extracted, a checking layout for detecting wafer pattern defects is obtain by adding the edge differences on the designed layout. Defects on the checking layout is identified to verify the patterns in view of processes before fabrication of a photomask.