The present invention provides a vehicle electronic control unit CAN interface automatic test system. The system is configured to rapidly complete the automatic test experiment of the CAN interface function of an electronic control unit and automatically generate detailed test reports of each CAN signal, and the automatic test experiment comprises: CAN signal analysis when the CAN perform normal communication, test of transmit-receive and routing functions and test of CAN signal replacement values when the CAN communication is abnormal. The present invention further provides a vehicle electronic control unit CAN interface automatic test system applying the system mentioned above. A test case file is directly and automatically generated by a CAN protocol database, the automation degree is high, the method is simple, the CAN receiving fault replacement value function and routing function automatic test is realized, one person can complete automatic test of thousands of CAN interfaces of a single vehicle electronic control unit only for half an hour, and a test report is automatically generated.