To investigate the effect of the external stationary shoulder on the formability and mechanical properties of friction stir welding joint，the self-developed NRSA-FSW ( non-rotational shoulder assisted friction stir welding ) was used to weld 2219-T6 aluminum alloy with the thickness of 4 mm plate. Mechanical properties of the joint were analyzed by tensile test and microhardness test. Optical microscopy and field emission scanning electron microscope were used to analyze the microstructure of the joint cross section. The results showed that the surface of the joint processed by NRSA-FSW formed without fish scales，flash，and thinning，and represented smooth appearance due to the scrapping effect of the static shoulder. Compared with the joint processed by FSW (friction stir welding) under the same condition，the softening zone of the joint processed by NRAS-FSW increased，and the microhardness distribution of the joint was more uniform. The average ultimate tensile strength of joints processed by NRAS-FSW was 323 MPa，approaching 72% of the base material，which was similar to the joint processed by FSW. Defects were not observed in the joint processed by NRSA-FSW. NZ (nuggest-zone) appeared as a "U" shape and the joint fractured in the NZ during tensile tests，which was ductile fracture.