Abstract: In order to deduce the engine control law during the helicopter autorotation,simulation was made to demonstrate the transient process of the engine when entering the helicopter autorotation condition using normal control law.Based on the existing control law,an improved law was brought forward by magnifying the differential gain of collective pitch "anticipator" and broadening the deceleration limitation.The simulation results show that the improved control law can satisfy the requirement of the helicopter,thus attaining an effective way for the control of the engine during the helicopter autorotation.