The Jiuzhaigou M_S7.0 earthquake on August 8, 2017 occurred in the vicinity of the Tazang fault, the Minjiang fault and the Huya fault, which belong to the strike slip type. The static and dynamic anomalies of gravity field can provide important physical field information for studying the structural properties of deep crust. We use multi-scale decomposition technique to separate bouguer gravity at different depths and give some explanation to gravity variations at different time space scales. The results indicate that the wavelet multi-scale results of the EGM2008 model and the measured gravity data are consistent. Through comparative analysis, it is found that the Jiuzhaigou earthquake occurred in the stress enhanced region. The variation of gravity field at different time scales has a certain scientific significance for further understanding of the potential earthquake risk trend.