The terminal guidance law is a key technology for the missile to attack target accurately,which has great influence on guidance precision of missile.To the problem of missile guidance in attacking the maneuvering targets,a variable structure guidance law was designed based on variable structure theory and father-offspring combined selection Genetic Algorithm (GA).Also,an adaptive reaching law and saturation function were used instead of symbolic function to reduce chattering of the system.Simulation results show that the variable structure guidance law based on father-offspring combined selection GA can find the global optimum solution and has high accuracy and robustness.Besides,it has low demand to the normal overload of missile,and the trend of the overload is stable during the guidance.The method has practical value in engineering.