A wireless switch cabinet bus connector temperature monitoring system based on MLX90621 infrared sensor was presented. The hardware and software of the wireless temperature acquisition system were designed by using a STM32 microcontroller, a MLX90621 infrared sensor and a nRF24L01 wireless communication module. The temperature data of high voltage switch cabinet bus connectors were measured by the non-contact MLX90621 infrared sensor array in real time and were uploaded by the nRF24L01 wireless communication module and the UART interface to the host computer for displaying. Because of the advantages of low cost, high stability and anti-interference, the system was suitable for the complex magnetic field environment in switch cabinets.