Abstract: A new model for grid task assign is discussed. This model can decompose the complicated computational task of 3D GIS into little blocks and assign to many computers to complete cooperatively and synchronously. By assigning 3D GIS roaming function to many computers to complete synchronously, which was originally done by only one computer, such questions as poor 3D vagile speed, high request for server equipment and roaming intermission, which exist in traditional 3D GIS roam and come of large amount of 3D data and complicated operation can be solved. In this system, grid computation was combined with 3D GIS roaming technique.