Abstract:The repeated gravity data of the Three Gorges gravity network are processed and analyzed. 11 differential and cumulative gravity change maps from March 2016 to September 2018 are obtained. The characteristics of gravity changes before the Zigui M4.5 and M4.1 earthquakes on October 11, 2018 are analyzed. The results show that: 1) since 2017, the gravity field of the epicenter region decreases, then increases, then decreases slightly before the earthquake occurs; 2) the two-year cumulative gravity changes show that gravity changes increase along the Xinhua-Longwangchong and Gaoqiao fault areas, which may be related to the preparation of these earthquakes; 3) as long as the observation network grid distance is reasonable and the data are properly processed, the regional mobile gravity survey network can give us potential detection capability for the change of gravity field before small earthquakes of magnitude 4.0.