Abstract: The research works on Global GIS(GGIS) becomes prominent in recent years.The current research works are discussed,and constructing a multi-level grid framework is the basis of GGIS is put forward.This multi-level grid framework is based on a uniform 3D Earth reference system and rely on Earth ellipsoid model.A lot of academic and technical problems exist and need to be resolved in sides such as multi-resources and multi-levels global spatial data integration,data expression on 3D ellipsoid surface,multi-levels grid coding and index technologies.Further analysis on the difficulties of these problems,and some reference solutions are also given.