Hydro-network is the standardized representation of the watersheds' river network by the Geographical Information System,and it uses the topological relationship to describe the spatial converge or diffusion of water flows in watersheds.In order to successfully simulate the spatial and temporal distribution of water flows in a watershed,it is vital to have an accurate topological relationship of the hydro-network in that watershed.The key to build a hydro-network model lies in defining the components of hydro-network and establishing the association among these components.Much attention was paid to the discussion of how to make a full use of the hydro-network's topological relationship in the distributed rainfall-runoff watershed modeling in this paper.An application example was provided and the studied result showed that using the hydro-network to represent the watersheds' river network was very helpful to the accurate simulation of the spatial and temporal distribution of water flows in watersheds.