Abstract: The extraction and correlation of fragment group targets in image sequences is a key technology in fragment parameter testing based on high-speed photography. In order to accurately extract and correlate fragment group targets, mixed Gaussian background modeling combined with adjacent frame difference method is used to extract the foreground; Through morphological processing, the interference of sparks and dust generated by explosion is eliminated, and the fragment target in the image is accurately extracted; A search method based on trajectory constraint is proposed to associate the same fragment target in the image sequence, which is proved to meet the test requirements by experiments. The key problems of fragment group target extraction and the same target association in image sequence in high-speed photography for fragment velocity measurement are solved.