In this article, an active fault-tolerant control method based on the optimized adaptive threshold and fault reconstruction strategy is proposed for the nonlinear mechatronic system with uncertain parameters and sensor fault. Firstly, the linear fractional transformation form is used to model the nonlinear mechatronic system with parameter uncertainty. The optimized adaptive threshold based on the particle swarm optimization is established to improve the fault detection performance in the presence of parameter uncertainty. Secondly, the dynamic equations of the system are derived by the analytical redundancy relations, and the tracking control strategy of the healthy system based on the recursive terminal sliding mode is proposed to realize the tracking of load position. An adaptive sliding mode observer is formulated to reconstruct the sensor fault when the fault occurs in the system, based on which the adaptive active fault-tolerant control law is established. The switching of control law can be implemented online by using the fault detection result. Experimental results show that the proposed fault detection and active fault-tolerant control method can accurately achieve fault detection and fault-tolerant control of sensor within 0. 06 s, which evaluates the feasibility of the method.