Abstract: In order to improve the effectiveness and practicability of sub-domain filtering method for identifying geological boundaries, the authors, based on the 1∶50000 high precision data of gravity in EQ block of the Yin-E Basin, used small sub-domain filtering method, a total horizontal derivative method, and an improved small sub-domain filtering method combined with a total horizontal derivative method to process the gravity anomalies. The results of each method were discussed in this paper. Then the fault structures were inferred on the basis of the results obtained by the combined method. Compared with the interpretation results of the seismic and electrical profile, the combined method can prove the fault structures, which shows the significance and effectiveness of this combined method. Theoretical model test and practical application results show that the combined processing method sharpens the field source boundary, enhances the lateral identification capability, highlights the geological boundary features, and even makes the fault structural framework clearer.