Abstract: In this paper, gravity changes of 2002—2005 and 2010—2013 were calculated based on the ground gravity data in 2002, 2005, 2010 and 2013 from the Crustal Movement Observation Network of China (CMONOC). We analyzed the spatial patterns of the gravity changes between the 2008 Yutian M_S7.3 earthquake and the 2014 and Yutian M_S7.3 earthquake, and the results demonstrated that there were common characteristics before these two earthquakes: ① Regional gravity anomalies appeared near the epicenters before these two earthquakes; ② The earthquakes occurred at the high gravity changing belts; ③ The epicenters were located near the zero line of the gravity transferring from positive value to negative value; ④ The earthquakes were mid-term predicted, especially the epicenter location, based on the regional gravity anomalies. At last, we discussed the relationship between the earthquake preparation and the tectonic activities based on the geological background in the north margin of Tibetan Plateau.

Key words: Gravity anomalies, Yutian earthquakes, Geological structure, Tibetan Plateau, Mid-term earthquake prediction