Aiming at the large field of view and lightweight requirement of solid imaging head-mounted night vision system, the optical system and mechanical assembly structure of binocular head-mounted night vision system were designed. Then, a high-strength carbon fiber epoxy was used for the shell material of the night vision system, and a new shell structure was optimized by Solid Works software. Finally, the thermal stability of the shell under extreme cold and high heat conditions was analyzed by finite element method. The simulation results show that the shell thermal stress of the night vision system is less than the yield strength of the material under the extreme conditions of -40 ℃ and 50 ℃. Moreover, the maximum strain has little effect on the imaging quality, display performance and mechanical structure of the optical system. The conclusion proves that the shell structure has good temperature resistance and reliability.