Abstract: A new idea for repairing groove defect in friction stir welded joints by friction stir brazing(FSB)with a pinless tool was proposed.In the experiment, Zn foil solder was used to wrap 6061 aluminum block to fill the crescent shaped groove defect with section shape of"U"in 6061 Al alloy plate, and then FSB was used to repair the defects.The results show that the original U-shaped interface be to filled and repaired obviously twists towards advanced side after defect repairing. The filled 6061 aluminum block and the 6061 aluminum block matrix are welded together, and the surface defect free zone and the alloying zone appear in the thickness direction from top to bottom in turn.The metal in the defect free zone is mixed under the combination of strong heat and force of the shaft shoulder, showing the characteristics of layered structure.The middle part of the U interface is the alloying area, the eutectic reaction of the base metal and the filled block with the Zn occurs, and the interfacial film removal and gap filling are realized. Alloying is also achieved at the bottom of the U interface, but discrete oxide film debris appears. The tensile strength of the FSB defect repaired joint can reach 90.7% of the sample treated by friction stir processing on the defect-free surface at the same speed.