Abstract: In order to compute the parameters of etched hole on metal surface accurately, as a example of etched holes on high voltage anode aluminum foil by DC, a rectangle simulation algorithm was designed based on the shape feature of the etched area. With the use of computer image processing techniques, the concave points were extracted on each hole’s contour and used to construct rectangles on the sample images to simulate these overlapping hole. Acceptable results of experiments had been obtained, further studies and analyses were based on the simulation results.