Abstract: With the help of ultra-high rotation speed friction heat,the connection of thin plate high-silicon aluminum alloy was realized by ultra-high rotation speed friction stir welding (FSW).The axial force in the process of FSW was greatly reduced,thus the welding deformation was reduced.This method had unique advantages in welding thin aluminum alloy.Taking the formation quality of weld and tensile strength of welded joint as the response values in this paper,the experimental design of main welding parameters affecting welding quality such as rotation speed,welding speed and plunge length,was carried out based on Taguchi method in order to optimize the ultra-high rotation speed friction stir welding process of high silicon aluminum alloy.The results showed that the significant influencing factors were welding speed and press amount.The optimum welding parameters were welding speed of 60 cm/min,rotation speed of 14 000 r/min and plunge length of 1.8 mm.The maximum tensile strength of friction stir welded joint for high silicon aluminum alloy was 129 MPa,which reached 97% that of high silicon aluminum alloy under the optimum welding parameters.Highlights:The ultra-high speed FSW process was optimized by Taguchi method,and a set of mature and reproducible FSW parameters for thin aluminum alloy were obtained.