Abstract: In this paper a 30′×30′global geoid has been determined based on a new theoretical method,which is quite different from the classical geoid modeling methods(Stokes method,Molodensky method,etc.).This new method takes full advantage of the precise Earth gravity field model EGM2008,digital topographic model DTM2006.0 and global crust density model CRUST2.0.The calculated 30′×30′global geoid is compared to the truncated 30′×30′EGM2008 geoid model and validated by GPS/leveling benchmarks(GPSBMs) in the United States and Australia.The results show that the calculated geoid performs at the same level as the EGM2008 geoid,and the standard deviation of their differences is 2.9 cm globally.The accuracy of the calculated global geoid reaches 28 cm in the United States and 14 cm in Australia.