With the development of high-speed railway in our country，and the increase in the number of Electric Multiple Units(EMU)，preparation of plans to overhaul becomes a heavy workload. Therefore，the study of maintenance scheduling optimization is necessary. Based on the optimization modeling，Genetic Algorithm(GA) is adopted to solve this problem. Through the simulation in Matlab，the fitness function can reach a steady state at a specific point；and the fitness function can get the optimal solution.