Abstract: For the problem of reducing the response time in air defense missile system, a micro electro mechanical system (MEMS) optical switch array was designed to control the signal transmission of subsystems in air defense missile system. The optical switch array which was constituted by 8 group double layer electrostatic comb structures,was used to control the On and Off state in every single subsystem. According to the LagrangeMaxwell equation, the electromechanical dynamics model was established, and the main parameters were confirmed including the mass, the elastic, the capacitance, the airfilm damp and so on. Then the parameters with genetic algorithm were optimized. The simulation result shows that the response time equals 0.627 ms, the steadystate displacement equals 4.724 m, the maximal displacement equals 6.801 m, the response time is one fourth of the original time. The result indicates that the MEMS optical switch array plays a role not only in reducing the response time, but also in ensuring the stability in air defense missile system.