A valley simulation system is developed based on Multigen-CreatorPro and Vega. Through a 3D models built on DEM data and ETM+ Image data, this paper implements a valley simulation system on MFC in Guanting and Miyun reservoir area, realizes the system function, and explores the technology detail of level of detail, multi-thread, virtual texture. By implementation of a real-time interactive 3D valley terrain simulation environment, it approaches a solution of building valley simulation system.