Abstract: To timely treat the emergent water pollution accident in Nanchang reach of the Ganjiang River, a hydrodynamic model for this reach was established by MIKE 21 model, and by using the model plus pollutant emigration model, the releasing and emigration processes of pollutant in the upstream were calculated. In the simulation, the hydrodynamic model was calibrated and verified by the measured hydrological data of the Ganjiang River in 2013 and the qualified model was used to simulate the pollutant release and emigration processes of emergent pollution accident in upstream under typical hydrological regime of wet, normal and dry periods. The results showed that in the cases of wet and normal periods, the pollutant mass can speedily pass through the drinking water intakes in 2 to 4 hours, but in dry period, the pollutant mass passes the drinking water intakes over 10 hours. The impact of emergent pollution accident on the water intakes is significantly influenced by hydrological regime of the Ganjiang River.