In this article, the effect of missile's exhaust jet on airfoil aerodynamic performance of UAV when missile launching was analyzed. The dynamic unstructured grids and turbulence model of k-omega two-equation model were adopted for simulating airfoil aerodynamic performance change affected by different distance in the process of initial launching stage. The result shows that the exhaust jet stream in the initial phase of the missile launching greatly changes the flow field structure around the airfoil and also has significant impact on the aerodynamic performance of the airfoil. This research finding has a certain reference value on the safety of UAV flight.