Abstract: The decorrelation and Gaussian smoothing method were was implemented in GRACE monthly gravity field products to obtain annual and seasonal gravity changes in Japan and its vicinity, as well as time series gravity changes of several points. Results showed regional gravity fields in Japan and its vicinity varied from positively to negatively and from area to area in five years before the Japan MW9.0 earthquake, ; obviously positive to negative gravity changes were formed in 1-2 years before the Japan MW9.0 earthquake; , and tTime series gravity changes of several points indicated the Japan earthquake displayed the similar time variation gravity phenomenon with the 1976 Tangshan earthquake; . These results reflected mass migration, mass movement and energy accumulation in Japan and its vicinity before the earthquake occurred, which provided evidence for the earthquake inoculation process research.