In this paper, the forces that act on the coffin-type launch of missile during its launch from orbit by order are analyzed by divided into three stages. The motion attitude of a missile out-of-orbit process is analyzed by ADAMS. Compared with the results of flight test, the velocity of pitch angle is consistent with each other at the time of departure from orbit. It is proved that the simulation model is reasonable. The results of the initial disturbance of the missile when it is out of orbit can be calculated by dynamic simulation, which provide significant reference for launching of missile.