A sliding model variable structure controller with auto-adjusted reaching law is researched in this paper. In the research, switch function s is taken as an error and reaching speed is adjusted by PID controller, with the intention of minimizing the traversing speed when arriving at the sliding model surface to reduce chattering and optimize the arrival time. According to the aero engine steady mathematic model, the sliding model variable structure control law is designed, the aero engine's sliding model controller based on PXI bus is constructed. The part-actual simulation results show that the controller is of swift response, tiny high-frequency chattering and is strong in robustness and tracking.