Abstract: Trajectory processing and analysis is now a research hotspot in database development, spatial information, and other related fields. Because of the complex scenarios between trajectories and directed lines, including topological semantics like intersections, touches, overlaps, returns, and stops, a key point oriented topological movement process model of trajectory-directed line is proposed, depicting semantic topological relations of trajectories over time with respect to directed lines such as direction relations, location relations, and semantic information. A planar spatial reference framework is established upon buffers building on the local effectiveness of direction relations. Then, 172 semantic topological relations, are classified into 14 basic topological relations, by detecting and analyzing the key points of trajectory-directed lines from a topological point of view. The resulting model expresses the topological relations of key points by means of character encodings with explicit semantics, and depicts complex movements of trajectories in relation to directed lines through key point encodings.