The performance of the solid rocket ramjet and missile influence each other greatly. Integral system project design of missile propelled by unchoked solid rocket ramjet can bring the performance of the solid rocket ramjet and missile into play and make them work in harmony，and improve the performance of the missile and ramjet. Multimethod collaborative optimization algorithm based on genetic algorithm、Powell method and pattern searching method is used to find the best parameters of the system project of the missile propelled by the unchoked rocket ramjet. Using the optimized parameters, the missile can get better system performance.