Abstract: A gravity net-work was set up through a group of gravity measurements in July, 1981 with three LCR gravimeters. The errors of measarement are less than 100 nm/s2. The detected changes of gravity with time in the Beijing-Tianjin-Tangshan area are described in this article.The results show that the gravity has increased by about 1000 nm/s2 in the area round, where the ground has subsided at a rate of 7-8 cm/year with Tianjin as the center of subsidence and gravity increase.At other stations, such as Baodi, Tangerli etc. gravity has also increased gradully, but the amplitude is smaller than that at Tianjin. The tendency of gravity change is smaller in the north-west part than in the south-east part of the area.