The metal flowing behavior in welding zone of FS welds has great influence on the welds mechanical performance. The friction stir welding (FSW) of 5 mm thickness plates of 1060 Al/3003 Al was carried out. The flow of metal during FSW was investigated by etching of the nugget in the welding zone of the 1060 Al/3003 Al. The flow visualization was examined in the range of welding parameters. The transverse and horizontal cross section was analyzed. The result shows that the process parameters influence the metal flow visualization greatly. With a high tool rotational speed and a proper welding speed, a steady and well-welded join can be produced.