Compared with traditional friction stir spot welding, refill friction stir spot welding can produce perfect weld without exit hole, so it has bright future in some cases including termination hole repair of friction stir welds. New research progress of refill friction stir spot welding in the recent years has been reviewed, such as development of welding equipment, study of welding process and forming mechanism, analysis of weld microstructure and mechanical performance, and exploration of dissimilar materials, in addition, several important fields are indicated which include welding robot, keyhole closure process, weld fatigue and bonding between Al with other material.