Aiming at the problem that the single membership function may have a sudden change in membership, a method based on the optimized combination of membership functions is proposed. By using the evaluation information of various membership functions, the evaluation information of various single membership functions is optimized and combined. Taking the operational effectiveness evaluation requirements of a certain type of rocket launcher as the research background, the underlying effectiveness index system is established, and the qualitative analysis and quantitative calculation are carried out by using the optimization and combination of membership functions, and the fuzzy comprehensive evaluation of the operational effectiveness of rocket launcher is realized. The results show that this method can improve the accuracy of the evaluation results, and has important reference value for the army to carry out actual combat training.