In order to solve the impact of the inclined launching missile jet flow on the front covers of launch canisters, the model of trajectory parameters and fluid field is built. To two working conditions are separately calculated including launching from the upper canister and the lower canister, the computioanal fluid dynamics and the technology of dynamic mesh is used to simulate the pressure distribution of every launch canister cover and the pressure curve. In addtonal to analyse to the impact of missile jet flow by changing the front mounting backward or the behind mounting forward. The simulaton result can provide some reference value to optimize the missile vehicular launcher.