This paper introduced an automatic extraction method for the drainage network deriving based on the combination of DEM with DRLN,with the concept of chain table being proposed.When searching upward from the basin outlet to determine the flow direction of every grid,the chain table is established to record the area of lakes and reservoirs,whose width is larger than a grid.The method introduced guarantees that the simulation drainage network is continuous and consistent with the actual river network.Thus the method to a certain extent settles the problem of distinguishing the actual depression and the false depression.The application in the Yellow River indicates that this method is simple and practical.