On February 12, 2014, a Ms7.3 earthquake struck the eastern region of the West Kunlun Mountains in Yutian County, Xinjiang, China. Immediate (Feb 20) field investigation following the earthquake shows that it produced surface ruptures at an altitude of 4600~5100 m. The surface rupture zone consists of a series of en-echelon tensional, shear-tensional to shear cracks, mole tracks, and sag ponds. Striking NEE—SWW, with a total length of about 29 km, the surface rupture zone is distributde along two subparallel faults, the Ashikule–Xor Kol fault and the south Xor Kol fault, which both split from the southwestern Altyn Tagh fault. Surface ruptures along the Ashikule–Xor Kol fault strike N63°~65°E for about 10 km, and are characterized by left-lateral strike-slip motion with normal component. Maximum sinistral and vertical displacements observed along this fault are ~0.7 m and ~0.4 m, respectively. Striking N54°~60°E for about 15 km, surface ruptures along the south Xor Kol fault are characterized by left-lateral strike-slip motion with thrust component, with maximum horizontal and vertical displacements of 1 m and 0.75 m, respectively. The N15°E-striking, right-stepping en-echelon tensional and shear-tensional cracks between the former two faults constitute a 5 km-long discontinuous rupture zone, with a sinistral transtensional behavior. North of the south Xor Kol fault, series of dextral transpressional surface ruptures striking N100°~110°E, constitute a 4 km-long, 2 km-wide secondary rupture zone. Compared with other strong earthquakes, especially strike-slip events recently, the surface rupture zone produced by the 2014 Yutian earthquake is the most complex one. The seismogenic faults of this earthquake are two splays at the southwestern end of the Altyn Tagh fault. These splays combined with the Gozha Co and the Longmu Co faults constitute the propagation of the Altyn Tagh fault in the SW direction. Considering about the location of the 2008 Yutian earthquake (Ms7.3), we suggest that the area along Guozhacuo fault is prone to great earthquake in the future. The SW extension of Altyn Tagh fault is the intense active fault in the western Tibet, so the great earthquakes on these faults is the result of the present tectonic stress field associated with the ongoing penetration of the Indian Plate into the Eurasian Plate.