Aiming at the trajectory design of ballistic missile in the powered phase, considering the influence of time deviation at the end time, the predictive static programming (MPSP) guidance method under the condition of free end time is deduced in this paper. Aiming at the free and fixed end time. Both flight time and control quantity are closed loop. The amplitude of controls at different times can be adjusted by adjusting the weight coefficient f c and weight matrix k R in the performance function. The MPSP guidance method for the powered phase is simulated and analyzed to verify the effectiveness of the free end time MPSP guidance method. The deviation of the flight path angle is in the range of 0.1 deg, and the altitude deviation is in the range of 1.0 m.