Abstract: In order to make the fiber-placing trajectory design software more adaptable, this paper sets to study the grid remodeling technology for the damaged area in mathematic model. It first compares two cir- cular point-sampling methods： ＂plane determined with three points＂ and ＂point determined through curva- ture＂ and proposes determining the discrete points of slice ring through ＂point determined through curva- ture＂; then repairs the damaged area according to the interpolated discrete points and adjacent grid of the damaged area, and smooths the damaged area and determines the discrete points of the slice ring. We next suggest smoothing algorithm of normal vector on the basis to guarantee the normal vector accuracy of dis- crete points around the slice ring and obtain complete information about the slice ring; and finally analyze the error between discrete points and their normal vectors of damaged location by comparing distribution of slice ring of complete mathematical model with that of damaged model with optical sphere. Finally, we carry out practical placement test and the feasibility and correctness of the algorithm proposed in the paper are verified.