With the increasingly enlarged project scale and rapid economic development,regional crustal stability has become one of the important factors restricting urban development in Beijing and Tianjin area.Based on a study and analysis of regional geology,neotectonic activity,modern vertical deformation of the crust,earthquake,modern structural stress field,rock and soil geology,geological hazards and outer power geological action by using Fuzzy mathematic method,it is suggested that four relative stable grades should be classified in this region,i.e.,stable,sub-stable,less stable and instable.