Three kinds of operational situation of relay guidance of surface-to-air missiles and the operational process of relay guidance are presented.Based on the guidance error and the successful probability of relay guidance, the model of guidance decision-making optimization is constructed. The model of guidance optimization is used to simulate and verify the relay guidance decision on surface-to-air missile. The simulation results show that the guidance optimization model can select the optimal guidance channel and provide a basis for the commander's decision-making.