For the problems that the unlocking mechanism was destroyed in the course of the Gatling gun test, the strength of the unlocking mechanism was analyzed and the cause of failure was found based on the finite element theory. Taking the maximum stress as the objective, the optimal Latin hypercube design method was used to analyze the sensitivity of the unlocking mechanism. The structure parameters which have a greater influence on stress is taken as the design variables, the ANSYS running program is integrated with isight multidisciplinary optimization technique under small changes in quality constraints, the objective is optimized by using gradient optimization MMFD. The optimization results show that maximum stress is greatly decreased; and it provided reference for improving performance of unlocking mechanism.