Abstract: Friction stir welding（FSW）, as a solid phase welding technology, is one of the main welding process of magnesium alloy. But there are still many quality problems to be solved in practical application. The research status of FSW joint quality and its influencing factors of magnesium alloy were reviewed. The macroscopic morphology, microstructure characteristics, microhardness, residual stress distribution and common defects of magnesium alloy friction stir welded joints were summarized. The influence of the stirring head geometry, size and welding parameters on the FSW joint quality was analyzed. It is pointed out that the joint quality is sensitive to the change of welding process parameters due to its poor plastic deformation capacity and fast heat dissipation, and the selection range of optimal process parameters is narrow. Therefore, the alloy content, chemical composition, and thickness of the workpieces should be considered when optimizing process parameters. Finally, the existing problems were analyzed and the future research direction was prospected.