In order to investigate the impact laws of different factors on the muzzle vibration, a multi-body dynamic model of the wheeled assault gun firing on the move was established and verified with experimental results. A road-surface spectrum model was built by using the harmonic superposition method, and the model was calculated under different road conditions and fire line heights. The influence of these two factors on the muzzle vibration was obtained. The model of a vertical stabilizer was set up, and the co-simulation was carried out to compare the muzzle vibration with and without stabilizers. The research results show that:the muzzle vibration amplitude increases with the increase of road roughness; the influence of fire line heights on muzzle vibration is nonlinear; the vertical stabilizer can effectively control muzzle vibration. Compared to the situation without stabilizer, the maximum muzzle altitude angle and altitude angle velocity amplitudes before firing decrease by 94.1% and 97.4% respectively, and the altitude angle amplitude of the muzzle after firing decreases by 16.2%. This research has certain reference significance for the overall design and engineering application of the wheeled assault gun.