Abstract: By simulating one dimensional water quality of natural channel,three groups of the basic solutions calculated from the initial pollutant concentration,the boundary pollutant concentration and the pollutant amount into channel,can be obtained respectively.Basing on the basic solutions,the pollutant concentration in any section of channel is expressed mathematically by a linear function of the pollutant amount.The optimization model for pollutant amount control is set up,in which the restraint conditions of the model are deduced from river's environment plan and the object function of the model from the function of pollutant treatment fee.The genetic algorithm is used to solve the optimization model successfully.