In power system, the temperature monitoring of high-voltage power equipment during operation is an important measure to ensure the stability and security of power supply. In this paper, the online temperature measurement system for high-voltage power equipment is designed and implemented. The system measures temperature by the method of divided voltage and transfers data by infrared light, supplied by thermoelectric generation based on the Seebeck effect. The hardware and software is accomplished in the principle of low-power consumption. Finally, the experiment of temperature data acquisition, system start-up time and receiving distance is carried out, and results show that the system can realize self-starting and cyclical temperature measurement.