Aiming at the problem of how to detect the SNR small moving target in the complex background, a new tracking algorithm based on moving target tracking forecasting and fuzzy algorithm was proposed. A space high pass filtering method is presented to improve the image quality for restraining the background noise and enhancing the dim target, then moving target tracking theory is used to forecast the location of target point, and then the memory was updated by using fuzzy theory, and the matching target point was searched for analyzing image sequence within a dynamic search rang. The experiment result shows that, the proposed arithmetic can calculate the small projectile trajectory before landing shoot by thermal imager, which verifies that the arithmetic can reliably detect small moving target of lower SNR.