Abstract: In order to identify the positions of the holes on paperboard produced by continuously fired bullet with a vertical target test system based on the image processing, a bullet hole recognition technique based on projection principle was put forward. The primary image was processed and divided into a number of segments by rectangular partitioning. The hole was successfully recognized and the center position of the hole was calculated using the formula described in this paper. The live fire experiment shows that this method can accurately calculate bullet coordinates and its measurement error is less than 1.5mm.