In order to this problem of manual testing bullet is low efficiency and low precision and low automatic degree, put forward the automatic test system for bullet steel core based on machine vision technology. This paper start with transmission and location and the best illumination and image collection set and image processing and recognition for bullet steel core, after pretreatment of image smooth processing denoise and image enhancement, which check size, bottom defects and surface defects. Accuracy of this system is verified through manual testing. Experiment result shows the testing time is shortened sharply, testing efficiency and accuracy also improved compare to manual testing