Abstract: As the carrier of the robot friction stir welding system, the joints of the robot are connected in series mode, which will deform during the welding process. The release of deformation during the ultra-thin plate welding process will lead to defects such as weld leakage, which restricts the robot friction stir welding system Application in the welding process of ultra-thin plates. In this paper, the robot friction stir welding process of 0.5 mm-thick ultra-thin 2024-T4 aluminum alloy plate was studied. The research indicated that: Due to the insufficient rigidity of the robot body, it is necessary to increase the plunge depth or the spindle speed to realize the welding of the ultra-thin plate, When the spindle speed is 2500 r/min and the welding speed is between 600-1000 mm/min, the joint strength shows a rising trend, up to 408 MPa, reaching 90% of the base material. The joint hardness shows a double "W"-shaped distribution. The fracture form is ductile fracture.