Because of the huge cost, the high demand of sensors and the limitation of observation for ballistic missile in outfield measure, the acquirement of measured data is certainly difficult. Moreover, as the radar echo is modulated by the high-speed and micro-motion of ballistic missile, the ballistic missile's RCS generated by electromagnetic software differs greatly from the measured data. In this paper, the Graphical Electromagnetic Computation (GRECO) method and the high altitude ballistic simulation is studied at first. And the linear frequency modulation (LFM) radar echo model for ballistic missile is analyzed. Then, a broadband echo simulation method designed for all-attitude RCS database of ballistic missile is put forward. The experimental results of the simulation show the efficiency of our method.