Abstract: In order to meet the requirements of operation control and parameter monitoring, a large number of sensors are arranged in the main and auxiliary systems of the reactor coolant pump. As the reactor coolant pump operates, the sensors may age or malfunction. In order to improve the weakness of the periodic tests and calibration schemes of sensors in nuclear power plants, the principal component analysis (PCA) was utilized for the condition monitoring of the reactor coolant pump sensors. The PCA monitoring model was established based on the operating data of the reactor coolant pump of a nuclear power plant, and the small drift fault and common mode fault of the sensors were identified by the model. The simulation results show that the monitoring model has a good effect on the condition monitoring of the reactor coolant pump sensors.