Abstract: The mixed integer linear programming model was established with the water source-sink matching as the constraint. To solve this model, the matrix of the source and sink matching was gradually adjusted, and the mixed-integer programming problem was transformed into a multi-step linear programming problem. The optimization method proposed in this paper, under the same conditions of the minimum amount of fresh water, was able to obtain a better water-using network with fewer matches, simpler structure and less investment costs. Two examples were given to verify this method.