Abstract: To improve the overall performance of the wheeled self-propelled gun, and to avoid the range and lethal area serious degraded when improving the firing accuracy, a collaborative optimization process and model were proposed, integrating with the interior ballistics model, exterior ballistics model, terminal effects model and a self-propelled gun general layout and firing dynamics model. Based on the method of integrated optimization, taking the minimum muzzle vertical angular displacement, the longest range and the largest lethal area as the multi-objective, the optimization was carried out and the Pareto optimization solution was obtained. According to engineering experiences, a solution was chosen, the muzzle vertical angular velocity decreased by 30.2% from 10.6(°)/s to 7.4(°)/s, the range increased by 1.63% and the lethal area added by 46.0%. The result is significantly better than the single-objective optimization aiming at the minimum muzzle vertical angular velocity. Studies show that the collaborative optimization model of trajectory and gun of a wheeled self-propelled gun can improve the overall performance of the wheeled self-propelled gun effectively and avoid the negative effect in single objective optimization where other objectives are degraded seriously.