Abstract: On January 7, 2025, at 09:05, an Ms 6.8 earthquake struck Dingri County in the Tibet Autonomous Region, resulting in significant casualties and property damage. The epicenter of the main shock was located in the Dingmucuo graben, in the western segment of the southern Xainza-Dinggye rift zone in the southern Tibetan Plateau, and the focal mechanism was identified as a typical normal faulting earthquake. The seismogenic fault is the normal faults in Dingmucuo graben, however, the distribution of surface rupture and geometry of normal faults, as well as the evolution model of this graben is relatively limited. This study discusses the seismogenic fault of the earthquake and the evolution model of the Xainza-Dinggye rift through the interpretation of remote sensing images before and after the event, field investigations of surface ruptures, and the relocation of the seismic sequence. Earthquake investigations revealed significant surface ruptures developed on both the eastern and western sides of Dingmucuo, forming a typical graben structure, while the northern segment primarily developed in the eastern part of the Nixiacuo, exhibiting significant displacement and resembling a half-graben structure. Notably, the surface rupture extends about 30 km in the graben showing a migration of the graben boundary fault into the basin. Furthermore, based on the seismic phase data recorded by the permanent and temporary stations, 4,312 high-precision location results were determined by using a double-difference relocation method. The epicenter of the main shock was determined to be at 28.51°N, 87.52°E, with a focal depth of 11.3 km. The aftershock sequence was consistent with the direction of the surface rupture, showing a ~NS distribution, with depths concentrated around ~4-17 km. The aftershock distribution revealed the coexistence of east-dipping and west-dipping fault characteristics. Based on the surface rupture and aftershock sequence, we conclude that the seismogenic fault for this earthquake is the eastern boundary fault of the Dingmucuo graben, with a dip angle of approximately 60-70°. The earthquake sequence is primarily concentrated in the upper crust and is likely a response to boundary stress resulting from the thrusting along Himalayan arc.