Abstract: A new unscented Kalman filter(UKF) based on the interactive multiple model(IMM) is presented to apply in the field of target tracking according to the characteristics of the weapon system of super-low altitude interceptors.A model set including current statistical model,constant velocity model and proportional navigation model is designed according to the motion characteristics of incoming targets,and every model works by using unscented Kalman filters independently.The output of the UKF-IMM is the weighted sum of the outputs of all parallel unscented Kalman filters.Simulation results show that the model set covers the motion mode of intercepted targets and switches rapidly among models.Using the UKF-IMM algorithm makes the fire control system of the super-low altitude interceptor track targets quickly and accurately.