In order to quantitatively study the influence of the shape of the stern on the resistance of the projectile, the computer-aided fluid dynamics method was used to numerically analyze the shape of the stern model with different mach numbers under the condition of supersonic speed, by analyzing and comparing the pressure coefficient distribution of the stern flow field, the stern surface and the bottom of the projectile ship. The results showed that the tail resistance of the projectile increases linearly with the increase of the tail cone angle; the bottom resistance of the projectile is affected by the area of the bottom of the projectile (shrinkage ratio) and the tail cone angle, and increases linearly with the increase of the shrinkage ratio; The overall drag coefficient of the projectile is related to the bottom resistance and the tail resistance. When the tail length is fixed, there is a tail cone angle that minimizes the drag coefficient, and its size is related to the flight speed of the projectile. When the flight speed of the arrow increases to 3Ma, the optimal solution of the tail cone angle reaches a stable value and its value is about 9.8°, which has a certain reference value for the design of the aerodynamic shape of the high Mach number arrow.