Abstract: The geological and geophysical studies show that there are large discrepancies for the distribution,strike-slip direction and tectonic styles of the faults in the southern and northern parts of the Qinghai-Xizang Plateau,and for the deep crustal architectures in the eastern and western parts of the southern Plateau.These comparative studies indicate that the horizontal differences become apparent in the styles and strength of the subduction and collision between the Indian continent and Eurasian continent.In the light of new findings in geological studies and recent development in lithospheric delamination theory and numerical modeling experiments,we have come to the conclusion that the above-mentioned differences are caused by the crustal thickening and oblique collision prior to the hitting of the Indian continent toward the Eurasian continent.