Abstract: During the radial stirring friction additive repair process, the excessive gap between the contour channels affects the positioning effect of the control points on the surface of the additive repair, making it difficult to confirm changes in height, width, and tilt angle. There are also problems with significant differences in the shape and contour of the repair area, as well as poor flatness. Therefore, a radial stirring friction additive repair shape control technology based on surface interpolation algorithm is proposed. Calculate the additive heat input and flow velocity during the repair process of the area to be repaired, calculate the height, width, and tilt angle changes of the repair area, and analyze the shape change pattern of the area to be repaired. Apply surface interpolation algorithm to calculate the weight factor values of the repaired shape, construct a surface model, set the interpolation function, and filter the specific control points of the repaired shape based on the shape of the area to be repaired. Based on control points, design a shape controller and combine it with a thermal cycle optimization function to achieve shape control for radial stirring friction additive repair. The experimental results show that the straightness tolerance value is small, and the shape of the repair area is basically consistent with the contour of the set repair area. The average contour is 0.93, and the surface flatness is 0.96, which can accurately control the shape of the radial stirring friction additive repair.