Three-dimensional velocity images of the crust and upper mantle beneath western China are obtained through seismic tomography by using P wave arrival times of local/regional and teleseismic events recorded in Chinese and Kyrgyzstan seismic networks. At shallow depths, most mountain belts and tectonically elevated areas are imaged as higher velocities, relative to adjacent sediment-filled basins and foreland depressions with lower velocities. At mid-lower crust depths, the Kyrgyz Tian Shan is underlain by lower velocity material and a distinct low-velocity zone in the south-north direction is observed between the eastern and western parts of the Chinese Tian Shan. The Moho of the southern Tarim basin has a greater depth over 50 km in front of the western Kun Lun, compared to the northern and western Tarim basin. Lateral heterogeneity within the upper mantle is apparent at depths from 71 to 571 km. The uppermost mantle beneath the Kyrgyz Tian Shan, Altay, Qi Lian, and eastern Kun Lun is characterized by low-velocity material that is probably related to the upwelling of hot mantle. The lithospheric thickness varies from 120 to 170 km beneath the Chinese Tian Shan and northern Tibetan Plateau to 200--250 km beneath the Tarim basin. Deep coupling pattern of the Chinese Tian Shan with adjacent provinces can be classified into the embedding, detaching and sinking, and underthrusting of lithospheric roots. In addition, the lithosphere of the northern edge of the Tibetan Plateau seems to be thickened, in contrast to the central part of the northern plateau. North dipping low velocities exist in the upper mantle between the Tibetan Plateau and provinces to its north, which might indicate mantle flow from the Tibetan Plateau toward surrounding areas, but it has been blocked by the thick Tarim lithosphere.