For the detection and tracking of dim point targets with SNR ＜2 dB, the combined SPRT and FSS method is given to accomplish detection in which likelihood testing are carried out twice to prune constantly.Firstly, the SPRT is developed aiming at the heuristic segments formed by correlation analysis. In order to avoid missing detection the threshold is chosen much lower. Secondly, by adding samples and choosing the one most similar to the heuristic segment to make state estimation FSS is implemented. This time we choose a higher threshold. Moreover in preprocessing the compound kernel estimation is designed to depress varying background clutter. Multiple experimental sequences validate that the method is more suitable for the dim targets detection and tracking compared with the scheme choosing the higher intensity pixel in tracking. It not only has perfect detection performance but also can greatly enhance tracking performance.