In order to prevent the mosaic line from passing through the visually significant features of orthophoto map thus damaging its integrity,a mosaic line extraction approach for orthophoto images is proposed,which combines edge information with optimized Linear Spectral Clustering (LSC) and improved A^* algorithm.First,the super-pixel segmentation theory of LSC is introduced for the mosaic line extraction,of which the classical LSC is optimized by edge intensity factor to effectively use the spectral information and edge information in orthophoto images.Second,the improved LSC is applied to the overlapping areas of two orthophoto images to obtain the boundary feature maps with various ground objects,and then the edge irregularity and isolated noise in the boundary feature maps are removed by mathematical morphology.Finally,the A^* algorithm is improved by replacing the original heuristic function based on Euclidean distance measure with Manhattan distance function,and then used to search the shortest path in the boundary map to quickly obtain the optimal image mosaic line.This approach is compared with related methods by using aerial orthophoto image taken by a UAV.The results show that the proposed approach can extract mosaic lines efficiently and with high quality,during which it effectively bypasses the visual salient features and meets the application requirements of orthophoto mapping.