Ecohat system is based on the study of eco hydrological process mechanism, starting from the basic water cycle process, adding nutrient migration and transformation process in the water cycle process, comprehensively considering the interaction of vegetation / biological growth, water cycle elements and nutrients in land water ecosystem. The ecohat system model is built on the basis of integrating the advantages of eco hydrological process models with physical and chemical mechanisms at home and abroad. After model adjustment, the model adopts parameters suitable for China's natural conditions to establish a localized database. Ecohat system realizes pixel based model operation by inputting regional spatial grid parameters. Therefore, ecohat system is a completely distributed integrated simulation system of eco hydrological process. Ecohat system includes four parts: water cycle, nutrient cycle, plant growth and aquatic environment response. Water cycle is the core of the system and runs through the other three parts. The simulation of water cycle in ecohat system includes five processes: rainfall infiltration, surface runoff, evapotranspiration, root water absorption and soil moisture; nutrient cycle mainly includes the simulation of nitrification, denitrification and ammonia volatilization in soil, the simulation of base cation cycle in soil, and the quantitative simulation of adsorbed phosphorus produced by soil erosion process; plant growth It includes vegetation ecological water use simulation, vegetation NPP (net primary productivity) simulation, productivity distribution process simulation and vegetation nutrient element absorption simulation.