Abstract: The interfacial shear test, interfacial bond test, lateral bending test and series temperature simulation test were carried out on the 10 mm-thick aluminum alloy-aluminum-steel composite transition joint, and tests on the interfacial shear and interfacial bond properties were carried out. The results show that the mechanical properties and post-welding interface properties of the composite transition joints can meet the requirements of relevant standards. According to the series temperature simulation experiment, it is recommended that aluminum-steel interface temperature shall not exceed 300℃ in the welding process.