Abstract: The underwater motion process of a submarine vertically launched missile from the tube in deep water was simulated by using a multiphase flow model, a Singhal cavitation model and dynamic mesh technique. The pressure drag coefficient of numerical results, being consistent with the references date as well, is compared with reference data, and the accuracy of the numerical method is demonstrated too. During the process of vertically launching from the tube, the shoulder cavitation geometric shape and the pressure distribution of submarine missile were obtained, the curves of pressure drag coefficients, friction drag coefficients and total drag coefficients were depicted, and the influence of shoulder cavitation to the hydrodynamic drag property of the submarine launching missile in deep water was analyzed.