Abstract: In this paper,the structure and function of the bolster are briefly introduced,and in view of the convex deformation of the cover plate during the water pressure and air pressure test of the bolster gas chamber in the production process,the material composition,mechanical properties,field welding quality influencing factors and design structure of the cover plate of the gas chamber are analyzed.The physical and chemical analysis and mechanical experiment were carried out through the specimen.Based on the theory of thin plate,the force analysis of the air chamber cover plate is carried out.At the same time,according to the boundary conditions,the air chamber cover plate is simulated by ANSYS.Determine the root cause of the cover plate deformation,and then complete the structural optimization of the bolus additional gas chamber,so as to solve the problem of convex deformation during the pressure test of the bolus additional gas chamber,so that the product performance has a better guarantee.