Objective Aiming at the problem that the strong coupling characteristics of knee-ankle-toe active prosthesis system in stance phase will lead to the decrease in control precision of prosthesis system, the method of exact feedback linearization was proposed to decouple the active transfemoral prosthesis system. Methods Gait data of human lower limbs were collected. Stance phase was divided into the early and middle stance phase and the last stance phase. The dynamic model of two stance phases was established. The prosthesis system in stance phase was decoupled based on exact feedback linearization decoupling. The integral sliding mode controller was designed to control the active transfemoral prosthesis. The co-simulation platform was built to verify effectiveness of the method. Results The decoupled system could improve the control accuracy. After decoupling, the calculated mean absolute error (MAE ) of knee and ankle in the early and middle stance phase was reduced to 0.001 1 ° and 0.002 6°respectively. Root mean square error ( RMSE ) was reduced to 0.014 7°and 0.023 6° respectively. At the last stance phase, the MAE of knee, ankle and toe was reduced to 0.011 1°,0.005 1° and 0.006 5° respectively, and the RMSE was reduced to 0.021 9°,0.021 0° and 0.012 9° respectively. The overall control error was reduced and the response speed was accelerated, and the prosthesis could operate stably in the co-simulation environment. Conclusions The decoupling method proposed in this study can effectively realize the decoupling of the transfemoral prosthesis system and lay the foundation for the prosthetic system.