Abstract: This paper focuses on the study of bathymetry prediction from satellite altimeter data and the use of FFT technique.In this study,the free-air gravity anomalies over the South China Sea are determined by the satellite altimeter data of GEOSAT,ERS-1,ERS-2 and T/P.And the 2.5'×2.5' bathymetry model in the South China Sea is calculated from the gravity anomalies by the inversion model given in this paper.After the analyses of the inversion results,some conclusions can be drawn.1) In deep-water area(>4 000m),the accuracy of the bathymetry calculated from gravity anomalies is better than that of the TBASE model by over 15%.2) The calculating results contain the significant system error.3) In the bathymetry calculating,eliminating the system error is helpful.4) In the shallow-water area,the accuracy of the results almost has not been improved relative to the TBASE model.