In order to meet the design demands of new gun systems or new types of projectiles, the interior ballistic charge design seems especially important. In this paper, a one-dimensional two-phase flow model is presented. The model describes the transient combustion of granular propellants in a gun, and pressure waves are considered as an objective. This study adopts a hybrid method to solve the problem. In the first stage, the non-dominated sorting genetic algorithm (NSGA-II) with a filter is employed to approximate a set of Pareto-optimal solutions. In the subsequent stage, a multi-attribute decision-making (MADM) approach is adopted to rank these solutions from the best to the worst. The ranking of Pareto-optimal solutions is based on the technique ordered preference by similarity to ideal solution (TOPSIS) method. In TOPSIS method each objective needs a corresponding weight coefficient, and a practical problem is introduced. Both the entropy method and linear analysis method are adopted to get two sets of weights for the objectives, respectively. The two pairs of final, best compromise solutions are compared for satisfying the designers aim. For the analysis of the results, a two-phase flow interior ballistic model for design optimization is established, and the hybrid approach could get a reasonable design scenario.