A 17 vol％ SiCp/Al-Mg-Si-Cu composite plate with a thickness of 3 mm was successfully friction stir welded (FSWed) at a very high welding speed of 2000 mm/min for the first time.Microstructural observation indicated that the coarsening of the precipitates was greatly inhibited in the heat-affected zone of the FSW joint at high welding speed,due to the significantly reduced peak temperature and duration at high temperature.Therefore,prominent enhancement of the hardness was achieved at the lowest hardness zone of the FSW joint at this high welding speed,which was similar to that of the nugget zone.Furthermore,the ultimate tensile strength of the joint was as high as 369 MPa,which was much higher than that obtained at low welding speed of 100 mm/min (298 MPa).This study provides an effective method to weld aluminum matrix composite with superior quality and high welding efficiency.