On June 30, 2012, an MS6.6 earthquake occurred at the border between Xinyuan and Hejing counties, Xinjiang Uygur Autonomous Region. It is the largest earthquake between the M7.1 Yushu, Qinghai Province event in 2010 and the M7.0 Lushan, Sichuan Province event in 2013.Based on seismic phase data of the earthquake sequence recorded by the Xinjiang Digital Seismic Network, we relocated the MS6.6 and its aftershocks by the absolute and relative location methods. The epicenter location of the mainshock is 43.429°N, 84.755°E, the focal depth is 21.8 km, and the aftershocks are distributed in NW direction. In terms of the waveforms of the M6.6 earthquake, we used the CAP method to make a grid search for the focal mechanism and the focal depth. The resulting focal mechanism solution includes 39°, 46°, 12° for the strike, dip, and rake angles on one plane and 301°, 81°, 135° on the other plane, respectively, and a focal depth of 21 km. So, the waveform inversion result is consistent with that by phase data. The strike and dip angles for the plane II of the focal mechanism solution are close to the Northern Edge fault of the Yili basin, and the relocated distribution of the aftershocks is also in agreement with the characteristics of the fault. Therefore, this fault should be the seismogenic structure of the Xinyuan-Hejing MS6.6 earthquake, which is of high angle and dip-slip in nature.