Abstract: An Mw7.1 earthquake, located in the central Pamir Plateau, struck Tajikistan on December 7, 2015. The location of the earthquake is close to Saraz Lake, formed in February 1911 when a nearby Mw 7.3 earthquake triggered a landslide that dammed the Murghab River. By studying the coseismic deformation of the earthquake, we can reveal the distribution of seismogenic fault and tectonic setting of the area, analyze the development of seismic geological disaster and evaluate the conditions of engineering geology. This paper observed the coseismic deformation by D-InSAR technology, using two periods of images before and after the earthquake from Sentinel-1A,which has advantages in wider range and higher precision. Combined with the geological background of the area and the focal mechanisms parameters from Global CMT and USGS,the following conclusions can be drawn:(1) the seismogenic fault is given priority to NE-SW extend with sinistral slip. It is rare in the central Pamir Syntaxis with priority to the north of arcuate thrust structure.(2) the entire coseismic deformation area is more than 120km in length and 80km in width, as well as the biggest LOS displacement in NW well is-60cm and biggest LOS displacement in SE well is 42cm.(3) the macro-epicenter is located in 30km northeast of Lake Saraz, which indicates this area is most serious damaged by earthquake.(4) the geological and geophysical information obtained from coseismal seismic deformation, observed by InSAR,can lay a foundation of tectonic stable analysis.