Abstract: For testing the shell fuses for missile, a set of automatic fluorescent magnetic particle testing system was designed. The structure and implementation ways of the system was designed, especially the image acquisition and processing part. Template Laplacian was used to sharpen the original image, template Prewitt was used for edge extraction, at last, area and perimeter were used as the characteristic value to judge if the workpiece could be accepted. Practical testing showed that, the testing resolution was as high as 0.01 mm, and could meet the testing requirement totally.