In order to improve the flight stability and shooting intensity of large caliber bullets, the shape optimization and aerodynamic characteristics of large caliber bullets are studied. Taking the 12.7 mm machine gun projectile as the object, the 3D shape of the warhead was established, and the radius of the curved part, the length of the curved part, the stern angle and the length of the stern were quantitatively analyzed. The numerical simulation was used to obtain the change curve of pressure cloud and drag coefficient during the flight of the warhead. The optimized warhead shape parameters are proposed, and the general influence law of shape change on the aerodynamic characteristics of the warhead is obtained. The simulation results show that the study can optimize the shape design of the warhead and has certain reference value for the shape design and aerodynamic characteristics of the large caliber bulle