Abstract: 5083 aluminum alloy plates were welded by MIG welding process with the domestic 5087 welding wire. The composition analyzer,electron microscope,vickers-hardness and material testing machine were used to study the microstructures and properties of welded joint. The results show that the wire meets the welding requirements. Vickers hardness is the lowest in the weld zone. The microstructure of each zone showed obvious difference,which was in line with the thermal effect. The welded joint has good mechanical properties and the weld strength coefficient is greater than 0. 9.