Abstract: In this paper,a mathe matical model for calculating the air demand of the aerator is established,and the target mathematical function for optimizing the shape of the aerator is proposed.The aeration character and the optimum shape of a prototype aerator are investigated.The optimum area of the air slot and the optimum height of the ramp or step are calculated.The results are in good agreement with the measured data.The method proposed herein may be used for preliminary design purposes.