Abstract: Mathematical models are simplified representations of the real world.Computer simulation models have been well accepted in the international hydrologic community for various reasons.This paper explored the role of simulation models in forest hydrological research and watershed management by using the MIKE SHE model as one example.Modeling concepts and the modeling procedures were reviewed.The authors stress that modeling is a powerful tool, but can not replace empirical investigations, and it should be used as an integral part of modern hydrological studies and comprehensive watershed management.The authors also discussed the needs of hydrologic modeling studies in China under the current nationwide reforestation campaign.