Abstract: Welds were obtained by CO₂ gas shielded welding with wires of various Al concentration. Based on the analysis of pores and slags in welds and the mechanical properties,the influence of aluminum on the weld quality was studied. The result shows that,as the concentration of Al element increases,the porosity of the weld decreases,and the number of slags decreases,however the volume of slags increases. When the concentration of Al in the wire is less than 4. 8 wt%,the strength of the weld decreases,while the toughness increases with the increase of the concentration of Al. When the concentration of Al in the wire is more than 4. 8 wt%,the strength of the weld increases,while the toughness decreases with the increase of the concentration of Al. A weld with less pores and slags and excellent mechanical properties was obtained when the concentration of Al in the wire is 4. 8 wt%.