Aiming at the accurate control of the overpressure state of the three-proof system of the armored vehicle, the influence of different factors on the overpressure state of the armored vehicle interior is studied based on CFD simulation analysis. Through theoretical analysis, geometric modeling, numerical simulation and simulation test, the influence of external flow field velocity, leakage area and fan speed on the internal overpressure was studied. The results show that the velocity of the external flow field is inversely proportional to the overpressure value, but the overall effect is small. The fan flow rate and leakage area have a significant effect on the cabin overpressure, and the relationship is a power function. It can provide scientific basis for operational decision-making, equipment maintenance and equipment improvement.