Unsteady Water quality model with multiparameter for the river network has been studied in this paper. The model reflects the characteristics of the unsteady flow with different direction and that of the unsteady water quality under aerobic, anoxic and anaerobic conditions. The model includes the various equations for DO, COD, BOD5, NBOD, NH4+-N.All parameters in the model have been obtained by the research for the observation on the field and the experiment in the laboratory. An equation of longitudinal dispersion coefficient has also been developed. Appling the computing method of dynamic coupling, the model has been verified by the data observed on field. The model has been applied to the program for controlling water quantity and water quality in order to improve the water quality of the river network of Wuxi city in China.