Based on the fundamental principle of earth gravity field, we derive the numerical integral expression for computing vertical gradient of gravity. According to new generation of 2′×2′ satellite altimetry gravity anomaly data, the authors obtain the distribution of vertical gradient of altimetry gravity in the western Pacific area. The RMS of new vertical gradient of gravity is about ±10.08E, compared with GSFC00_DGZ data. In addition, some analyses and discussions were introduced. Finally, some possible approaches for further research are brought forward.