In order to evaluate the tunnel stability in advance and avoid disaster, using the massive construction information, a system of geological prediction ahead of working face during tunnel construction is developed based on 3D GIS. The overall structure of the system, the 3D database structure of tunnel, the system development plan, construction method of 3D model of geological body around tunnel, and the prediction method are introduced. It is used in a typical tunnel case, and the results show that the system is scientific and convenient, and can reduce geological disaster during tunnel construction.