Abstract: The vertical launching technology of the underwater vehicle by using the gas curtain is a new underwater launch technology. By means of numerical simulation,this paper studies the relationship between the shape of the gas curtain and hydrodynamic characteristics of the underwater vehicle under different gas jet speed during the vertical projection. The results show that,in the process of the underwater vehicle launching from the tube,the vehicle can pass through the least radius of the gas curtain successfully on the condition of different gas jet speed,and in the process of the underwater vehicle exiting the water,the total drag coefficient of the vehicle decreases independent of the Mach number of the gas jet.