Major problems in welding Al-7020 include shrinkage, porosity in welds and loss of strength in the heat affected zone. Thus it is important to examine the mechanical properties and reliability of welds.In this study, a series of experiments was carried out to determine the mechanical properties such as micro-hardness distribution, tensile strength, porosity and residual stress distribution of the Al-7020 weldment made by pulse-GMA welding.The results of the experiments are as follows.(1) The micro-hardness of weld metal and heat affected zone was lower than that of the base metal.(2) The tensile strength of the deposited metal was much lower than that of the base metal.(3) The porosity in weld metal zone was negligible under the adopted conditions of experiments.(4) The residual stress in the weld metal was lower than that of the heat affected zone, because the weld metal was softened.And the micro-hardness distribution, the tensile strength and the residual stress distribution of the weldment in the as-welded condition were compared with those of the weldment after heat treatment.