An infrared guidance system with high-pressure nitrogen refrigeration was introduced, and a noise reduction optimization design was conducted for a photoelectric pod with a sealed structure. To design an air return hole for a photoelectric converter refrigeration unit, fluid simulation methods were used to obtain optimized structural parameter values, system verification passes, background noise reduction, and improved system detection sensitivity. The simulation results verified the correctness and feasibility of the optimization scheme, which has engineering-guiding significance for the system design of photoelectric weapons.