To study the underground geological structure and faults in the Xizang (Tibet) plateau, Shaanxi Geological Survey conducted a survey of 1：∶1000000 regional gravity in Tingri—Muztagata area from 2003 to 2006. The writers have processed and analyzed the gravity data.Based on the data as well as other geophysical and geological data, the bouguer gravity field is divided into 7 subareas whose gravitational characteristics and geological significance are showed. The writers have curvefitted the gravity data of Tingri—Muztagata profile and interpreted them geologically. In this way the quantitative model of crust there is gained. 30 faults are identified and classified and some important faults are particularly explained. The results show that the gravitational subarea’s characteristics corresponds to the tectonic subarea’s characteristics; those important border faults between massives situated at the edge and inner of the Xizang (Tibet) plateau are manifested clearly by the gravity field; the faults are categorized into 3 groups according to their extending direction: nearWE、NE and nearNS. NearWE faults are backbone faults.