By using the software of GDPAS-MRG，we got the gravity field variation of different time and space scales before and after the 2002 Taiyuan earthquake，and the 2003 Hongdong earthquake. We then performed a wavelet multi-scale decomposition of 2000～2004 gravity field variation of Shanxi Province，and analyzed the accumulative changes of different time and space scales of gravity field in terms of wavelet transform. The above results demonstrate that: (1)The two earthquakes just occurred in the gravity gradient belt and zero line. (2)We can obtain the dynamic variation of different space-time scales of gravity field using wavelet transform，and many weak details are enhanced when the order is increased.