The target tracking algorithm of the traditional short-range active protection system does not take into account the vehicle motion factors, but the actual vehicle motion parameters have a great influence on the target tracking accuracy, which leads to a decrease in the overall protection performance of the system. Therefore, the radar target tracking algorithm on the moving base must be studied. Under the moving base, the radar measurement space registration was realized. Then based on the UKF algorithm, an improved UKF algorithm was proposed by introducing radar radial velocity measurement information and adopting scale symmetric sampling strategy. Through Monte-Carlo simulation, it is verified that the algorithm can significantly improve the target tracking accuracy and convergence, and meet the real-time high-precision tracking requirements of the short-range active protection system.