Abstract The total horizontal derivative and the amplitude of analytic signal defined by the first derivative of gravity field data cannot balance the amplitude of shallow and deep anomalies. Inorder to solve this problem, we propose an improved boundary identification method of inclined derivative geological body using gravity full tensor gradient data called NTDM. The NTDM shows improvement in the convergence, noise suppression and boundary resolution of the new method. We obtain fourteen structural units with clear boundaries and use NTDM for the gravity data in the middle-southern segment of Tan-Lu fault zone. Then, using gravity vertical deviation data, we inverse the tectonic stress field, crust-mantle density difference. The results show that there are significant differences in horizontal direction and spatial correlation. The maximum difference of tectonic stress is about 16 MPa, and the crust-mantle density difference is about 0.2 g/cm3. The dense area of tectonic stress isolines corresponds well to the boundary of structural unit and seismic distribution. The direction of the maximum stress of the middle part of Tan-Lu fault zone is NEE-EW and the southern part is EW-NWW, and the overall direction is EW. The results are in good agreement with those obtained based on focal mechanism solution, in-situ stress measurement and GPS inversion.