In this paper,friction stir welding（FSW） was applied to join 6005 A-T6 aluminum alloy side wall profiles. By using macroscopic metallurgical analysis,tensile tests and bending tests,optimal welding parameters were identified:spindle speed 800 r/min,welding speed 1000 mm/min,axial force 14.5 k N,shoulder plunge depth 0 mm. For a certain spindle speed and welding speed,axial force and shoulder plunger depth had less effects on the tensile and bending properties of joints. The axial force should be controlled critically. Overhigh axial force led to friction tool press down excessively,which damaged the base metal. The axial force being too low induced tunnel defects due to the insufficient stirring in base metal. As the shoulder plunger depth increased,flashes became easy to form.