Abstract: The establishment of the watershed hydrological model at the macro-scale and the simulation of the sediment delivery in the catchment are the key research issues in the watershed hydrological modeling, in which the coupling simulation of the water and sediment in the watershed is the key issue. On the basis of the hydrological model based on Representative Elementary Watershed which is applicable to macro-scale, the paper introduces the sediment erosion and delivery to build up the water-sediment coupling model. With the simulation of the changing channel slope in the water-sediment delivery, the model achieves the water-sediment coupling modeling in nature. To deal with the limitation of the channel coding of binary tree, the virtual computation unit is used into the model. The high-resolution remote sensing image is employed to measure the river width and it provides a new method for the hydrological modeling in the ungauged basins. The results shows that, the performance of the hydrological modeling is very good, and simulated and observed sediment discharge are consistent in terms of total sediment load and intra-annual process. Most of the channel slopes of the watershed are steady and parts of the reaches are in the evolvement.