Aiming at solving the difficulties of choosing and planning in the weapon systems development problems, a bi-objective optimization model was proposed to minimize the capability gaps plus the total risk values, and to look for the best development scheme by comparing different combinations of weapons based on the given capability requirements. The total budget limitation, annual budget constraint and the planning period were taken into account in this model. A solving algorithm, based on non-dominated sorting genetic algorithm-Ⅱ and differential evolution, was presented to obtain the Pareto set. The technique for order preference by similarity to ideal solution method was employed to reach a final compromise solution．A case was studied to demonstrate the effectiveness of the proposed model and hybrid algorithm, which can support the decision making on the weapons development and planning.