Abstract: Welding tool is the core of FSW, which plays a significant role on joint quality. In this paper, a non-rotational tool system was employed to join 6061-T6 and AZ31B alloys. Joint formation and mechanical property of joints based on traditional and non-rotational shoulder processes were mainly analyzed. The results showed that compared with traditional tool, the smooth surface appearance was attained and complex Al/Mg intercalated layer structures and bended Al/Mg joining interface formed in nugget zone based on non-rotational shoulder tool system, improving mechanical interlocking effectively. Moreover, the thickness of intermetallic compounds layer was also smaller than those of traditional tool, resulting from the severer stirring actions and heat sink induced by the non-rotational shoulder. The maximum tensile strength of joint obtained by non-rotational shoulder reached 137 MPa, which was improved by 28% compared with traditional tool.