Most aluminum alloys used for structural purpose are either heat treated or cold worked in order to develop higher mechanical properties. When alloys with enhanced properties are welded, the heat of welding reduces the strength in localized regions (named Heat Affected Zone) in and immediately adjacent to the welds, which makes the study of the bearing capacity of welded beams become more complicated. Nowadays it will be long time and cost much if only through experimental method to study the welded aluminum beams. Thus a finite element (FEM) analysis method is tried in the paper. By comparison the test results gotten with the ones of the FEM analysis, it is verified the feasibility of utilizing it to study the welded beams. Furthermore, a large number of results produced by this method validated the formula proposed in China aluminum code.