1350 industrial pure aluminum with 3 mm in thickness was joined by frictional stirring welding（FSW） . Influence of different ratios of ration speed to welding speed（ω/v） on microstructure and mechanical properties of the frictional stirring welding joint was investigated. The results reveal that joint exhibits coarse surface morphology with the formation of tunnel hole when ω/v is 5.0 r/mm

and S-shape defects are observed in the joint when ω/v is 8.3 r/mm

however

the joint with desirable appearance and defects-free can be observed when ω/v is more than 8.3 r/mm. Area and grain size of the stirring zone are increased with the increase of ω/v value

however

the change of micro-hardness of stirring zone is different from the ω/v value change. Tensile strength and elongation of the joint is increased in range of 5.0～10.0 r/mm to the maximum value at 10.0 r/mm

and then decreased as ω/v value increases. SEM observation shows that dimples and tearing edges similar with the matrix material can be observed in the joint with ω/v more than 8.3 r/mm

which verifies that the joint exhibits excellent plasticity.