Aimed at the stress relaxation of giant size welding assembly of 5A06-H112 aluminum alloy cabinet, several welding processes were studied. The TIG and MIG welded joint microstructures were examined out. The ulti鄄 mate strengths, residual stresses and the hardness of the TIG joint were measured in comparison with the MIG weld鄄 ing. The results showed that the residual stress of the joint in the welding assembly of aluminum alloy relaxes following the descending鄄after鄄rising curve. Due to the lower energy input and multi鄄layer welding process, TIG has the differ鄄 ent ability to reduce the stress relaxation contrasted with MIG. The method which combines TIG with extending 8 to 10 aging days enables the stress relaxation weakens, and confines the assembly爷s dimension stabilization finally.