Abstract: We propose a new approach of line simplification based on geographic-feature constraint.The approach divides line into initial curve bends with constrained Delaunay triangulation model according to geometrical shape of line.It identifies basic bends and complex bends by the curve bend detection method,acquires the contiguity and hierachical levels relationship by curve bend tracing method,and fully achieves structural method of line shape.Neighboring geographic features in effective spatial neighborhood of line were gained and putted into curve sub-bends.This approach design the rules of bend selection and the whole flow of line simplification.The experimental results show that the algorithm is excellent in the aspects of holding the shape of line feature,geographic-feature consistency,and undergoes a high simplifying rate with a simple parameter.