Using the dynamic nested grid and the CFD method to simulate the separation trajectory. To predict the trajectory of the object from the airplane, a numerical simulation program based on the POD method was established. Using the CFD simulation trajectory as samples, changing the flight Mach number and the angle of attack as an example, introduced the implementation steps of the POD method to predict the trajectory from the airplane. Results from the numerical example, based on the existing sample data,the POD method relative to the CFD method can greatly reduce the computation time, and the results obtained by the POD predicted good with the results from CFD method, provides a quick easy prediction for the separation trajectory in engineering applications.