Abstract：Starting with 6 P wave tomography profiles across the South China block, the authors approached 3D structure of the South China lithosphere. The South China block can be divided into three parts bounded by Qin-Hang fault zone and Chuan-Xiang-Gui rift. To the southeast of Qin-Hang fault zone there is Cathaysia lithosphere which is a part of the SE Asia-West Pacific low velocity lithosphere, formed by intrusive uplifting of ashenospheric materials. To the west of Chuan-Xiang-Gui rift is the Upper Yangtze lithosphere, which is hot near the surface but has a high velocity root at depth. On the west part of upper Yangtze block, Paleozoic mantle plume in the Panxi area formed a magma chamber at the crust-mantle transformed zone, resulting in basalt eruption in vast areas. Between the Chuan-Xiang-Gui rift and the Qin-Hang fault zone is mid-Yangtze lithosphere, which is cold and whose resistivity is low. The thickness calculated by heat flow and magnetotelluric sounding reached 300 km.