Abstract: According to the decision-making characters of the multiple-attribute and multiple-index system for comprehensive evaluation of waterway net,a linear changing operator in is developed by use of the rule of "Rewarding the Good and Punishing the Bad".A decision-making model of gray correlation for comprehensive evaluation of waterway net is established by finding the positive and negative ideal percepts and calculation of the correlation degrees between the appraisal percept and the positive and negative ideal percepts.Calculation results of a practical example show that the model can be used in the comprehensive evaluation of waterway nets with simple and rapid calculation,high resolution,and good stability.