Abstract:We combine ground geodetic data(absolute gravity, GNSS), surface and underground hydrological data, and GRACE satellite gravity data. Based on the long-term variation of absolute gravity at Jixian GNSS datum station in 20 recent years(1998 to 2018), we calculate and analyze the gravity effect caused by different physical signals, including the vertical displacement of the earth’s surface, groundwater and surface water load. Then, the characteristics of long-term gravity variation of each influencing factor are obtained, and the following conclusions are drawn through in-depth analysis and study: The long-term variation of absolute gravity at Jixian datum station from 1998 to 2018 shows a downward trend as a whole, and the change rate is about -1.64±0.53 μGal/a. The well water level data from 2004 to 2017 shows that the groundwater at Jixian GNSS datum station has an obvious downward trend, with a change rate of about -0.66±0.07 m/a, and the gravity effect is -1.94±0.22 μGal/a. It is the most important factor that affects the gravity change of this point. A comprehensive analysis of the long-term variation characteristics of the ground absolute gravity and other gravity effect factors shows that there is a gravity rise of about 0.43±0.58 μGal/a at Jixian datum station. It may be related to the upwelling of high-density matter at the top of the upper mantle in the capital circle area.