Abstract: The overlapping grid technique and symmetric TVD scheme are used to simulate the flow field of lateral jet interaction for two missile configurations.The vortex and wave structures of this flow field are shown and the topology of separation flow is given according to the computational results.The interaction effects on aerodynamic characteristic are studied.The influence of the location of surfaces on the amplification of jet thrust is investigated.The computational amplification factor and the moment coefficient of interaction are also given and well agreement with the experimental data.