Abstract: The NURBS theory was used in the point cloud processing and surface reconstruction of blade. Since the surface of blade is designed through optimization of structural mechanics, aerodynamics and strength analysis, the shape of blade is a kind of complex free surface. The least square method was used to denoise the outliers in fitting the local surface process and segment according to curvature threshold. The bi-cubic interpolation Coons surface in form of B-spline was taken as the basal plane, and the scattered point cloud was approached to the non-constraint surface. According lo optimization theory, the control points of the Bézier surface were determined by the iteration theory. Finally, the 3D model of worn blade was recovered by splicing and trimming surfaces based on NURBS, which provided an ideal model for subsequent welding repair.