The traditional conceptual hydrological model has its localization that cannt simulate and partition different runoff components accurately. However, after dividing vertical layers and horizontal grids to the watershed, a distributed hydrology model established based on the physical foundation and runoff producing theory could analyse the mutual effect and coupling simulation about surface water and ground water with considering hydraulic connection of different runoff components. This paper applies LL- Ⅱ distributed hydrology model developed by professor Lilan and GIS technology to Tianfumiao Reservoir watershed in Huangbohe River in Yichang City,and simulates and forecasts daily flow for this watershed on surface water and ground water coupling. Finally, through the application of an illustration, this method obtains a good simulated result.