Aiming at the problem of cracks on the surface of the air rudder in the guided rocket, the finite element simulation analysis is carried out. By simulating the boundary constraint and curing pressure load during the curing process, the location of the larger shear stress is consistent with the location of the actual crack; In the process of composite molding, excessive external pressure will lead to shear crushing effect between the metal core grid position of the air rudder and the composite material, which will increase the residual stress of the structure, especially when the thinner composite material area such as the root of the rudder core has a large shear force, which will lead to penetrating cracks at the corresponding position of the rudder surface; By optimizing and controlling the process parameters, it can effectively improve the situation of too much pressure and too fast cooling rate, and then prevent the occurrence of surface cracks. The results show that the analysis provides a reference for the subsequent structural design and manufacturing of the air rudder.