Abstract: Based on the data of absolute and relative gravity observations of the national major scientific project China Crustal Movement Observation Network from 1998 to 2008，gravity field in the North-South seismic belt region and its dynamic variations are obtained. The evolution characteristics of regional gravity field and its relationship with the seismic activity before and after the 12 May 2008 WenchuanMS8.0 earthquake are studied in the sight of dynamics. The dynamic variation image of gravity field reflect the portentous information of the development and occurrence of Wenchuan MS8.0 earthquake more clearly. The variations of gravity field show spatial and temporal inhomogeneity, at the same time, however, they reveal certain relation associated with the development and Occurrenceoftheearthquake, and associated also with regional tectonic activity.