3D geological modeling refers to integrating the kinds of geological data in 3D underground space to form 3D quantitative model. The dynamic update method of 3D geological model is always the hot topic of researchers. Pointing at 3D modeling and visualization, the author team has developed a 3D visualization platform based on IDL and formed the basic modeling tools including data processing from 2D to 3D, 3D objects editing, surface fitting, surface cutting etc. which have been applied in water resources and hydropower projects practically. On the basis of the existing 3D modeling tools above-mentioned, this paper classified the 3D modeling methods according to the specific objects of 3D spatial models expressed (such as terrain surface, water surface, bedrock surface and so on) and designed 3D modeling process as relatively fixed processes. Besides, the paper achieved dynamic update method of 3D model modification process based on database and script-driven approach. This method fits for 3D visualized simulation in which the engineering data needs updating constantly with the progress of works, and has been applied in 3D modeling of water resources and hydropower projects. The anticipated results have been achieved.