The invention relates to an automation testing device of vehicle-mounted ECU (Electronic Control Unit). The automation testing device of vehicle-mounted ECU includes a load testing platform, a bus analysis device and a host computer, wherein the bus analysis device is connected with the load testing device through a CAN bus, and is used for connecting each vehicle-mounted ECU to be tested throughthe CAN bus; the host computer is connected with the bus analysis device, and is used for transmitting CAN control signals to the load testing platform and the each vehicle-mounted ECU to be tested through the bus analysis device according to a preset CAN communication matrix corresponding relationship; and the load testing platform is used for connecting the each vehicle-mounted ECU to be tested,outputting the corresponding test signals to the each vehicle-mounted ECU to be tested according to the CAN control signals transmitted from the bus analysis device, acquiring the output signals of the vehicle-mounted ECUs to be tested, and uploading the test signals and the output signals to the host computer through the bus analysis device. The automation testing device of vehicle-mounted ECU can effectively reduce the DV (Design Verification) testing cost of vehicle-mounted ECU, and can improve universality.