In view of the problem of correction of the end of ballistic trajectory of mortar controlled by impulse engine, this paper built a ballistic trajectory model based on impulse engine control and simulated the trajectory controlled by impulse engine, fired at different distance from the target, under the certain impulse engine parameters. By simulation the impulse engine’s correction capability was obtained. And the simulation result shows that the correction effect to the X axis direction is greater than to the Z axis direction, and that the correction to the X axis positive direction is greater than to the X axis negative direction and the correction to the two directions of Z axis direction is the same. So the research is important to the selection of the fire time and number of the impulse engine and serves as theory reference.