On the basis of the data obtained from the GPS networks in the Bohai basin and its adjacent areas in the past decade, the present-day tectonic movement and internal deformation as well as strain field in this region are analyzed.The Bohai basin and its adjacent area have a counter clockwise rotation related to the Eurasia plate as while a consistent SE ward movement with a velocity of 2.2-7.2 mm/a. The horizontal deformation field in this region shows an asym-metric four-quadrant distribution. There is relatively consistent NE ward deformation in the western part of Bohai basin and relatively consistent SW ward deformation in the northeastern part, and the two parts are in a NE-SW ward compressive status; there is relatively consistent SE ward deformation in the southern part of Bohai basin and relatively consistent NW ward deforma-tion in the northwestern part, and the two parts are in a NW-SE ward tensile status. In the Bohai basin and its adjacent areas, the principal compressive strain axis is basically in the NEE-SWW direction and the principal tensile strain axis in the NNW-SSE direction, which are totally consistent with the dominant direction of principal comp ressive strain axis of tectonic stress field in this re -gion obtained with the geophysical method. The principal direction of present-day tectonic stress-strain field in this region has been in stable status since 1969.

According to the plate tectonics theory and 3D finite element modeling, considering the historical evolution of stress field in North China, the variation of internal tectonic stress field in North China are simulated numerically when applied forces on the boundary of north China have changed. Changes of direction of collisions of Pacific plate and India plate with Eurasian plate induce important loadingunloading effect. If the direction of applied forces from Pacific plate turns southwards that leads to the loading in the north part and unloading in thesoutheast part of North China, whereas the direction of app lied forces from Pacific plate turns northwards that leads to the unloading in the north part but loading in the southeast part of North China. The direction of applied forces from India plate turns southwards that leads to the loading in the middle region of Shanxi and Tangshan－Bohai aeras, whereas the direction of applied forces from India p late has turned northwards that leads to the loading in the east and south part and unloading in the mid-west part of North China.

By analyzing the characteristics of fault-crossing displacement variation i n the Capital area before and after the Ms 5.1 Wenan earthquake of Hebei on July 4,2006, and combining the characteristics of regional fault activities and regional seismicity in the area since 1970,it is concluded: 1) Since 2000 the thrust activities of NNE directional faults in the Capital area have been increasing, it shows that the present principal compressive stress in the Capital area is in NEE direction; 2) The Cap ital area and surrounding regionsmay enter the next active period of medium-strong earthquakes, theWenan earthquake marks the beginning of this period; 3) The vertical activities of NE directional faults in the Cap ital area and surrounding areas change strongly, the amp litude of variation may be taken as an index for medium to longterm earthquake prediction.