Abstract: Based on the flow characteristics and pollutant distribution of Dagu River,QUAL2E model,a comprehensive water quality model,was chosen to simulate and predict water quality in the Qingdao section of the main stream of Dagu River, with BOD₅,COD and nitrogen as indexes for simulation and prediction.Some important quality parameters,such as BOD decay coefficient（k₁）,reaeration coefficient（k₂）,BOD settling coefficient（k₃）,COD decay coefficient and dispersion coefficient,were determinated through experimental simulation and by using the model rating method and referring to related literature.The simulation results were verified and showed that the predicted values agreed with the measured ones extremely well.The sensitivity analysis of BOD₅,k₁,k₂,and Q（flux）was also carried out.The results showed that the parameters influencing the concentration of oxygen were lined in the order of Q,k₂,BOD and k₁ in sensitivity.Q is the most sensitive parameter,indicating that hydraulic parameters of the river have a greater influence on DO.The water quality simulation of Dagu River provided basal data for calculating the water environmental capacity of Dagu River and implementing the pollutants total control,as well as scientific evidence for the supervisors and decision-makers of water pollution control.