Abstract: The terrain data of transmission line corridors is an important basis for the design and operation of transmission lines, and contour data is an important form of terrain expression. A contour extraction method for transmission line corridors based on airborne LiDAR was studied to address the issues of low work efficiency and safety hazards that currently require on-site survey of terrain data for transmission lines. Firstly, the airborne LiDAR data is filtered using fabric simulation filtering to obtain ground point information. Secondly, Delaunay triangulation is applied to the ground point data, and the triangulation is used for equal height interpolation calculation. Finally, based on the triangle relationship, connect the equally high points to obtain contour lines. Experimental results have shown that this method can effectively extract contour lines from LiDAR point cloud data, replacing manual field surveys, and has high engineering practical value.