Abstract: Based on the Saint-Venant equations of one-dimensional unsteady flow，on the basis of nodeflux strict balanced，and combing with flood and moist control and drainage regulation design，it optimizes pump works in-out flow calculation and node design of hydrodynamics model for river networks.It discusses the river network simplified method，boundary conditions and the output of the model in view of the outer river brake and channel improvement project of jiaodong lianwei drainage area in Panyu district of Guangzhou city.