Abstract: Based on the reviews of current multi-contour reconstruction algorithms, a new algorithm named cut-and-sew (CS) is presented, in which a pair of control points is introduced as incision to cut and spread out a pair of contour lines to form two parallel line segments, after the coordinate transform of contour vertices and making one contour line corresponding to the other one in the same pair. Seeking for the corresponding relation between contour line vertices, the 3D shape's facial triangular pieces which conformed to Delaunay principle are generated, thus solving the reconstruction problem of two adjacent contour lines which are much different in shape and number of polygon vertices. The algorithm is proved efficient in the application for 3D geological modeling based on sections and inspirable to resolve other similar problems.