To study the distribution law and influence factors of the missile’s outlet attitude, the force analysis of a certain type of amphibious vehicle is carried out, and the dynamic model of the amphibious vehicle launching on the move under the excitation of random waves is established. The launch process of amphibious vehicle is simulated for many times, and the simulation results are analyzed by statistical method, and the statistical results are obtained. The results show that: under the excitation of random waves, the missile’s attitude distribution law conforms to normal distribution; the smaller the average wind speed and the navigation speed, the better the missile’s attitude; when the amphibious vehicle’s tail sails in oblique waves, its launching safety is higher.