Abstract: The characteristics of weld seam appearance, porosity, key hole behavior and mechanical properties of welded joint were analyzed with 4 mm thick aluminum alloy welded by dual and single fiber laser beam-TIG arc hybrid welding process, respectively. The results show that, when the backside melting width is similar in laser-TIG arc hybrid welding process by using dual laser beam and single laser beam, and comparing with single beam laser-TIG arc hybrid welding method, the continuity and uniformity of backside weld seam appearance are better when the dual beam laser-TIG arc hybrid welding method was used. The porosity is reduced by more than 50%. The average surface area of key hole is larger; the coefficient of surface variation of key hole is smaller. But the tensile strength, percentage elongation of fracture, microhardness and microstructure of hybrid welded joint are similar by using dual laser beam and single laser beam.