Objectives: Continental dynamics studies the motion of energy and matter in the earth and the accompanying information propagation, and the asthenosphere in the upper mantle is one of the key parts of the material motion inside the earth. Because of lack of precise methods, little is known about the geological action process of the asthenosphere. In the Qinghai—Xizang(Tibet) Plateau, the resolution of threedimensional tomography of seismic waves in the past was not high, and it is difficult to accurately locate the mantle structures. Methods: We collect and organize the digital observation data from hundreds of local seismic stations, select more than 260000 rays and their traveltime for the 3D seismic inversions, obtaining 3D velocity images of scale of 1°×1°×20 km, and greatly improves the accuracy of 3D seismic velocity images. Thus the work provides new possibilities for correct positioning of the geological structures of the lithosphere and asthenosphere. Results: According to the imaging results of the seismic 3D velocity tomography, there are highvelocity bodies exist on the bottom of the asthenosphere, corresponding to the ancient or new TethysOcean subduction plate, which appear in the Qinghai—Xizang(Tibet) Plateau, Sulu and Iran. They lay on the 410 km discontinuity in the bottom of the asthenosphere along the front of the corresponding suture lines. The clear and stable position of the high velocity anomalies indicate that the old Ocean Subduction Plates occurred delamination down to the bottom of the asthenosphere after they subducted into the asthenosphere. Comparing the velocity structures of the mantle between the Qinghai—Xizang(Tibet) Plateau and Sulu orogenic belt, it is speculated that the delamination caused the light elements mass of the asthenosphere upwelling onto the continental lithosphere, resulting in magma and volcanic activity. The upwelling also reduces the thickness of the crust of the collisional orogeny and increases the thickness of the continental lithosphere. After about 100Ma, the subduction of the ocean debris will be under abrasion by the hot asthenosphere, causing continental volume growth, accretion and cratonization. Conclusions: The delamination of the old ocean plates in the asthenosphere plays an important and irreversible role in mass motion between the lithosphere and asthenosphere after the subduction of the oceanic plate. The delamination process also plays an important role in the balance of matter and volume stabilization in the asthenosphere.