Abstract: The problems of correcting gravity tidal observations and indication of gravity anomalies used in earthquake prediction in China are systematically studied in this paper. The correc-ton problems of the theological model of the instrument, inertia of the earth and the effects of the ocean loading, air pressure, underground water on gravity tadal recording data are also discussed in detail, the related results are also given in the paper. The problem of indicating non-tidal information in stational gravity data is discussed. The perporties of several different data processing filters are compared from the theoretical point of view.