Different rotation speeds were used on bobbin friction stir welding 6005 A-T6 aluminum alloy of 4 mm thickness. Through the research of tensile test,bending test,metallographic experiment and microhardness test,the results show that with the travel s peed of 500 mm/min,the surface of the welded joint is regular and no cavity is found in the weld at the rotation speeds between500 r/min and 600 r/min. The microhardness of the stir zone has a little change,the width of the heat affected zone increases,the lowest microhardness is found in the advancing side with the rising rotation speeds. Tensile strength of the welded joint first increases and then decreases with the rising stirring speeds,when the rotation speeds is 500 r/min,the tensile strength reaches the peak of 220 MPa,which is 86.47% of the tensile strength of the parent material.