Based on the SSJ model, the kill probabilities of missile system and gun system are concretely analyzed. The influence coefficient of the SSJ system to anti-aircraft gun missile system's average fires is advanced and the target intercept ratio model of the anti-aircraft gun missile system under SSJ is obtained. Setting the jamming distance 20km, J/S 0.6981, the application and the simulation results show that the intercerception ratio model is effectively under the influence of the SSJ system. The research will help to know the combating performances of the anti aircraft gun missile system, and enhance the combating survival ability of the penetrating aircrafts.