Abstract: Anonline temperature monitoring system for excitation carbon brush of water turbines based on radio frequrency identification（RFID） is studied and designed. The system utilizes an RFID temperature measurement chip installed inside the carbon brush holder for monitoring the working temperature of carbon brush in real time, which enables to visually display the temperature change curves and set the temperature thresholds for alarm. The system has been tested onsite in the actual operating environment of the water turbines, and it is verified available for continuous online temperature monitoring of carbon brush with high temperature measurement accuracy and fast alarms, which offers an effective means for the condition monitoring and fault alarming of key equipment in hydropower stations.