In oder to solve the problem of multi-target date association in dense clutter, a novel algorithm of data association was proposed based on weakening operator self-adepted fuzzy C-means. First, in the new algorithm, the weakening operator was used to reduce the randomness of effective echoes, then the self-adepted FCM algorithm was used to cluster effective echoes, and the resulting cluster centers were considered the final measurement of the targets. Finally, the nearest neighboring algorithmwas used to associate the culster centers with the tracks. Simulation results show the algorithm has a better tracking and associating accuracy than FCM data association algorithm and the CPU occupies a relatively short time than JPDA algorithm.