Abstract: In this paper, the formulas for computing geoid undulation and vertical deflection are modified by some special techniques. It has obviously quickened the convergence speedof the summation terms, and decreased the truncation error. A new method for deter-ming oceanic geoid from gravity anomaly using Hotine function has been worked out. The accuracy of geoid undulation computed in this paper is better than 1 meter;systematic differences between seasat geoid and oceanic geoid are at the half-meter level. From the geoid charts some correlation of the oceanic geoid with ocean bottom to-pography has been shown, that the main characteric of the oceanic topography can berepresented by the oceanic geoid.