The temperature detection in the electrical power system is a principal method to avoid the equipment failure or accidents. In recent years, the use of the wireless temperature monitoring technique is an important manifestation of the smart electrical power system. In view of the development demand of smart grid, this paper designs a temperature detection node which is based on radio frequency communication technology. The node is composed of temperature sensor DS18B20, ultra-low power SCM PIC18LF14K50 and radio frequency transceiver chip MRF49XA, which can realize three working conditions of dormant wait, data sampling and wireless communication. By setting up the key parameters under different working conditions, the average power consumption of the temperature detection nodes is tested and compared, and the power consumption rules of the nodes are summarized. On this basis, a self-powered supply management unit based on LTC3588-1 chip is designed for the temperature detection node, which adopts the mature and reliable inductive current energy take-up technology to meet the self-powered supply requirements of the temperature detection nodes. The research shows that, when the node is in full electric state, once the energy source is cut off, the node can continue to work steadily for 47 h, which can maintain the normal work of the temperature detection node until the power grid is restored to normal operation.