The mechanical characteristies for friction stir welding (FSW) of 5083-O Al alloy were evaluated. The results show that in FSW at 800 r/min and 124 mm/min, a weld defect is observed at the start point. However, the button shape at the end point is good and the stir zone has a soft appearance. At 267 mm/min, a void occurs at the button. A slight weld defect and rough stir zone are seen both at the start and end points at 342 mm/min. Moreover, at the bottom, a tunnel-type void is observed from an early stage to the end point, and at 1 800 r/min, a weld defect can be found from an early stage to the end point. These defects are rough with imperfect joining due to excessive rotation speed and high physical force. Weld fractures relative to rotational and travel speeds are observed at the stir zone. The optimum FSW conditions are a welding speed of 124 mm/min and a rotational speed of 800 r/min. The results show that in FSW at 800 r / min and 124 mm / min, a weld defect was observed at the start point. However, the button A slight weld defect and rough stir zone are both both at the start and end points at 342 mm / min, at 267 mm / min, a void occurs at the button. min. Moreover, at the bottom, a tunnel-type void is observed from an early stage to the end point, and at 1 800 r / min, a weld defect can be found from an early stage to the end point. rough with imperfect joining due to excessive rotation speed and high physical force. Weld fractures relative to rotational and travel speeds are observed at the stir zone. The optimum FSW conditions are a welding speed of 124 mm / min and a rotational speed of 800 r / min.