Aircraft gust response refers to the transient change of aircraft flight parameters ,the structure load conditions in the event of gusts. The additional aerodynamic gust loads will lead to changes in aircraft flight status , gusts over substantial value will affect the performance and safety of flight. In view of this situation , this paper based on CFD technology to solve unsteady N-S equations , introduces " grid speed" in the computing grid to simulate gusts , and research aircraft gust response in time domain. First calculate aerodynamic characteristics of three-dimensional aircraft model SWIM (Simple Wake Follower Model) in the trailing vortex , CFD calculation results with the results of wind tunnel experiments , literature CFD results are in good agreement ; Then simulate the flight path of SWIM diving across trailing vortex field , achieving the CFD-6DOF trajectory simulation of SWIM in the trailing vortex. Trajectory simulation results show that the jitter , sinking , changing flight conditions , intense flip phenomena occur while SWIM flying in trailing vortex are similar with the trajectory characteristics of aircraft flying into the wake vortex.