For improving the precision of the altimetry gravity calculated by the inverse Stokes formula, the non-singular transformation is introduced to solve singular integral problem in the inverse Stokes formula when the geoidal height of the innermost area is expressed as double cubic polynomial, and a formula to calculate gravity anomaly of this area is derived. The singular integral formula deduced in this paper has a high precision based on theoretical model analysis. Computation is carried out on a test area, which consists of 1201120 geoidal height data with a resolution of 2′12′, the results illustrate that the contribution of the...