In response to geometry seamline detection with average separation of overlapped region and beautiful shape for remote sensing images mosaicking considering complex background, a fast automated geometry seamline generation approach along skeleton was proposed on image analysis. Firstly, different kinds of region for image mosaicking were marked in view of background value. Secondly, each block overlapped region to be processed was considered as one image object, the footprints of these image objects were detected and re-marked following specific rules pixel by pixel until the overlapped regions to be processed don′t exist. Finally, the geometry seamline along skeleton was marked on four neighborhood search. The experimental result shows that even if the overlapped region is complex polygon considering background value, the fine seamline can be quickly automatically selected. The algorithm robustness is better than those algorithms on graphic analysis.