Disclosed is a high voltage signal and low voltage signal sampling and transmission system based on a high voltage MCU, including a sampling unit, a high voltage processing unit, a communication unit and a low voltage processing unit. The sampling unit includes a bus voltage sampling module, a phase voltage detection module and an IGBT temperature detection module. The high voltage processing unit adopts the high voltage MCU, and the high voltage MCU is configured to perform state monitoring and analog-to-digital conversion on the three-way analog detection signals, and output a digital signal to the communication unit; the communication unit adopts an isolated communication unit to transmit the three-way digital signal converted by the high voltage MCU to the low voltage processing unit; the low voltage processing unit adopts a low voltage MCU to realize sampling and communication of high and low voltage sampling signals.