Three dimensional earth figure is dynamically expressed by utilizing 3D visualization theory and OpenGL technique. In this paper, the global data structure and data transformation, modeling the digital earth, the method for calculating normal vector as well as the rapid transformation of global grid data into triangulated network data are studied and realized. The experimental data of global terrain is from The JGP95E 5' Global Topographic Database edited by The Defense Mapping Agency and NASA/Goddard Space Flight Center(GSFC), and the height above geodetic datum calculated by WDM94 model which was provided by WTUSM. Experimental results indicated that the mathematical model of global terrain and earth figure and their visualization methods are reasonable and practical. The visualization model created by means of the method mentioned above could be rotated and enlarged. Also the vertical scale could be changed in order to display the small undulation of the earth surface.