The Yecheng-Shiquanhe profile runs over the western Tibetan Plateau from the south margin of the Tarim Basin, crossing the west Kunlun orogeny, to the east of Karakorum. The authors applied body waves to 3-dimensional inversion of travel time residuals and outlined the deep tectonic pattern of the northwestern Tibetan Plateau. An image was obtained, showing that the Tarim lithosphere is subducted southwards underneath the west Kunlun orogeny at an angle of 40° and a depth of 280 km. Surface structures are well expressed in the image and can be further traced in deeper levels. The prominent finding is that the Gozha Fault and Karakax Fault are likely to join together beyond a depth of ～200 km, which is the very zone of active seismicity.