Abstract: Based on the Saint-Venant equations,the advection-diffusion equation and the uncertain mathematics theory,both a one-dimensional hydrodynamic model and a uncertain water quality mathematical model are established.The Preissmann implicit four-point scheme is used to solve the Saint-Venant equations,and the explicit scheme is used to solve the advection-equation.Two reasonable computational codings of hydrodynamic and water quality for the river network are conducted.The model considers the controlling projects of pump and brake,rainfall-runoff.The Computer program of the unsteady flow is compiled by using the three-level solution method for river network to solve the water level and the discharge at different cross sections.The data connection of the two sub-model is realized.The differential water quality model is computed based on the uncertain mathematics theory,including two unascertained parameters at the first time.According to the model proposed,both the interval values of pollutant concentration and the respective corresponding veliability can be obtained directly.The case shows that the hydrodynamic model and the uncertain water quality model for looping river network are reliable and can be applied to water quality regulation project and the water environmental assessment.