The invention discloses a vehicle-mounted mobile charging device monitoring system, belonging to the field of electric vehicles. The vehicle-mounted mobile charging device monitoring system comprises a main processor, an electric energy metering circuit and battery monitoring circuits, wherein the electric energy metering circuit and the battery monitoring circuits are connected with the main processor; and the main processor is connected with three ways of CAN bus interfaces, wherein the first way of the CAN bus interface is connected with all vehicle charging circuits in the vehicle-mounted mobile charging device, the second way of the CAN bus interface is connected with all power switching circuits in the vehicle-mounted mobile charging device, and the third way of the CAN bus interface is connected with all battery monitoring circuits. The vehicle-mounted mobile charging device monitoring system has the technical effects that the potential difference between the main processor and the battery monitoring circuits is reduced, the potential difference between the vehicle charging circuits and the power switching circuits in the vehicle-mounted mobile charging device is reduced, the influence on the communication and monitoring functions of the whole vehicle-mounted mobile charging device monitoring system by the potential difference is reduced, and the interference resistance of the whole vehicle-mounted mobile charging device monitoring system is enhanced.