Gun box withstand tremendous impact load in the process of recoil. According lightweight requirements of weapons systems with the needs of high-strength, the different thickness gun box was analysed by finite element analysis, through path planning and data mapping, strain distribution pattern of the axial and circumferential stress and stress conditions was studied to gun box reliability and precision guided turn the curve rail impact; and according to the results of the topology optimization to optimize the structure of the gun, contrast gun optimized to meet light weight and high strength requirements had better structural characteristicsand stress distribution.