Abstract: It is meaningful to tracking ballistic missile in boost phase precisely by forward ground-based radar for the whole anti-missile defensive system. The paper presents a new method to track ballistic missile in boost and post-boost phase based on prior database. At first, the paper extracts characteristic dynamic parameters of ballistic missile, and analyzes the sensitivities of these parameters and gives a time invariant dynamic model with parameters; then the paper simulates the performance for tracking ballistic missile in boost and post-boost phase with IMM and IUF algorithm. Compared with other dynamic models and algorithms, this new method has much higher tracking precision and by calculating the model transition probabilities, it can classify the ballistic missiles and indicates the burnout time accurately. The simulation results validate the new method.