An earthquake is a mechanical process in which elastic strain energy is released suddenly once stresses in the focal region are accumulated to a critical extent. Therefore，there exists an intrinsic connection(http://cn.bing.comdictsearch？q＝.&FORM＝BDVSP6) between the process of earthquake preparation and the cumulation of crustal strain. In this paper，strain rate field is calculated by the use of GPS velocities observed in the Chinese mainland with twice interpolations approach. Interpolating the scattered GPS velocity data of Chinese mainland and its adjacent areas to grid point values by Kriging，we then calculate the strain rate from these nodal values of each element similar to derivative of shape functions(essential Lagrange interpolation function)in finite element algorithm，and obtain the stable distribution of strain rate field in the studied area. The results show that the strain rates in China and its adjacent areas on the whole are high in the west and low in the east. The strain rates are evidently larger in the western region of China than those in the east bounded by North-South Seismic Belt. To the east of the belt，strain rates are very low，especially in southern China. In addition，the tectonic stable regions such as the Tarim Basin and Ordos Basin show low strain rates. Moreover，the calculated results suggest that the seismic activity is closely related to the strain rates in China and its adjacent areas. There is a very close relationship between strain energy density and seismicity. Where strain energy is large，seismicity is high，and vice versa. We also found correspondences between seismicity and the maximum shear strain rate and surface strain rate. Therefore，the calculation of strain rate field will provide an important reference for seismic hazard assessment.