Abstract:The approximated formula of conversion between the geocentric latitude and the geographic latitude from a basic formula is presented in this paper.And using the recent value of the ellipticity of the Earth(satellite orbit betermination method,1977),we have given the conversion coeffi-cients(βandγ)and a new α-φlist.There is some difference about 5 angle seconds(corresponding to the distance on the surface of the Earth-about 150 meters).It is not neglected for some aspects of GEONOMY to require higher precision of the latitude conversion.Finally,there is a brief discussion on some approximated formulas in this papaper.