Abstract: An endpoint fusing method is proposed for hand-drawing 3D projection sketches based on the tolerance zone of each endpoint with variable radius(VRTZ).Adjacent endpoints of sketch lines will be fused if their VRTZs intersect with each other and the candidate endpoints all fall into the region of intersection.When two adjacent sketch lines are recognized as conic curves,their endpoints are reset at one of their intersection points.A simplified approach is developed to evaluate the intersection of two conic curves.According to the geometric type of the adjacent sketch lines which represents either a boundary edge or a silhouette line,the endpoint fusing process are classified into several cases,each is associated with a specific fusion rule.The precise positions of endpoints are finally obtained by integrating with the object 3D shape reconstruction.The method has been tested against a number of hand-drawing 3D projection sketches and the results are satisfactory.