The formulation of the test specification is mainly to determine the content of the network to be tested. In the entire network development process, the network test specification should be carried out after the network requirements specification is completed. The purpose of the network test is to confirm whether the ECU products provided by the supplier meet the requirements of the network requirements specification. Because of this, the formulation of CAN network test specification must be based on CAN network requirement specification. The test specification needs to include all the test items and the description of the test environment requirements, test steps, and test tool requirements required for each test item to be tested.