Based on the characters of parafoil homing trajectory, SerretFrenet frame was used to describe the shortest distance from the current position to the trimming trajectory. Then, using the theory of small disturbance linearization, it showed that the error equations were time invariant. The transform function between the control and the position error could be found from those error equations, and could be used to design the trajectory controller directly. The position errors and velocity errors which are inputs to the trajectory controller could be solved by analytical method, which greatly simplify computation. The effectiveness was testified by the result of example.