With improving computer penormance and advancing simulation techniques, a growing number of softwares are being developed for visualization of investigation results in geotechnical problems. It is a very important subject for geological site investigation to understand or predict if there would be any hazardous geological conclition that might cause any increase of construction costs or an extension of construction period. A 3-D (three-climensional) visualization technique may be one of the powerful tools to overcome an uncertainty problem of geologica] site investigatior. The paper describes an overview of a newly developed geotechnical 3-D interpretation system for the purpose of applying the 3-D visualization technique, GIS (geographic information system) and D/B (database) to tunnel design and construction. VR (virtual reality) and 3-D visualization techniques are applied in order to develope the 3-D model of characteristics and structures of rock mass. D/B system for all the materials related to site investigation and tunnel construction is developed using GIS technique. This system is very useful for civil engineers to make a plan of tunnel construction at the design stage and also during construction with the advantage of improving the economy and safety of tunnels.