Because of the limitations of wireless Internet of Things technology and battery life, the development of smart manhole cover technology is slow. In this paper, a self-powered smart manhole cover is proposed. Thermal power generation technology is used to convert the temperature energy under the manhole cover into electrical energy. To increase the temperature difference near the bottom of the manhole cover, the heat insulation layer and the radiator are added, and the temperature gradient is increased by 5 ℃ ~ 10 ℃ . The experimental equipment of thermoelectric generator module was built, and the thermoelectric generator was tested and analyzed. The results show that the thermoelectric module generates 7. 92 J electric energy with an average power of 2. 2 mW under the temperature difference of 13 ℃ in one hour. Based on NB-IOT technology, smart manhole cover monitoring node is designed to monitor the tilt angle of manhole cover. Through the dormant standby method, the power consumption of the node system is reduced. The node acquires and transmits data once and consumes 0. 185 J power. The node standby current consumption is only 87. 45 μA. The combination of selfpower generation and low power consumption Internet of Things has verified the feasibility of thermoelectric power generation as the energy supply of the smart manhole cover.