The problems which include difficulty in assembly, joint quality control, large distortion after welding exist
in assembly welding process of heavy-thickness aluminum rectangle chassis. The corresponding fixture types were chosen
for different type of structure plates. According to the characteristic of chassis type bodies deformation after welding, a fixture
for the chassis was designed. Based on these works, electron beam welding is successfully used in the chassis assembly
welding process. The chassis after welding meet the specifications of design requirement. The results show that the designed
fixture and process is practical, and this research is advantageously used in solving these problems