Abstract:The anomalous variation and dynamic evolution characteristics of the gravity field in the Capitol region in the seismogenic process of the Wenan Ms5.1 earthquake on July 4,2006 are studied. The results show that the updownup variations of gravity before earthquake are the obvious reflection of mediumshoutterm anomaly. The dynamic patterns of gravity field reflect clearly the evolutionary process of the gravity field: quasihomogeneous statenonhomogeneous stateearthquake occurrence.There is similar evolution characteristics of the gravity field between Wenan Ms 5.1 earthquake and of Luanxian ML5.0 earthquake on January 20,2004.