The capture of the Paleo- Jinsha River which once flowed into the South China Sea as well as the formation of the First Bend of the Yangtze River not only resulted in a sharp change of the filled materials in basins, but also recorded the tectonic movement mechanisms of the northern margin of the South China Sea. However, owing to shortage of direct evidences, the timing and origin of the east- flow river and the Great Bend formation is still debated. Thus, this study performed numerical modelling based on both TTLEM and LIFEE models to simulate the connection and incision processes of the Tiger Leaping Gorge. The results show that the present- day deep- cutting Tiger Leaping Gorge resulted from two phases of rapid exhumations. Its initial connection formed at ~15 Ma during the Mid- Miocene contemporaneous with the folding of the anticline along the Tiger Leaping Gorge, corresponding to the widespread large- scale strike- slip faulting with thrust component of the Dali fault system. Since Quaternary, deformation pattern shifted from transpression into transtension. The Tiger Leaping Gorge started a new rapid incision owing to the crustal elastic flexure with an exhumation amount of ~3 km, resulting in the sent landscape. Combining other results, we suggest that with the continuous underthrusting of the India Block to the Eurasia Block, several major changes in tectonic movement mechanisms have been triggered by the eastward material migration along the southeastern margin of the Tibetan Plateau. These major changes not only caused the shifts of faulting characteristics, resulting in the capture and reorganization of regional large- scale river systems, but also were related to the expansion and formation of the South China Sea.