While a sensor is in service, its measurement value can drift, and the drift value will increase with time increasing. For the performance degradation of a  ensor in a non-linear system, based on modified particle filtering algorithm, this paper proposes a method to monitor sensor’s performance degradation in real time. The system states are estimated on the basis of real-time estimation of drift. The proposed method can detect and track degradation process of a sensor in a dynamic system, and provides safeguard for the operation of dynamic system. Simulation results varify the effectiveness of the proposed method.