Urban street light monitoring system uses power line carrier communication technology to realize street lamp single lamp control. Is conducive to the digital management of urban street lamps to meet the needs of social development, in response to the national green lighting program. Because of the power line as the communication medium, which itself has great limitations. The low voltage grid is a timevarying frequency selective fading channel. Signal attenuation, impedance change and noise interference are the most important factors influencing the channel characteristics of low voltage power network. Therefore, it is necessary to adopt a route relay scheme and a modulation technique with strong adaptability to meet the needs of low voltage power line carrier communication network. In this paper, the OFDM modulation and demodulation method and the routing relay strategy using ant colony algorithm are used to optimize the optimal path planning problem in the data transmission process, and improve the quality of power carrier communication.