Abstract: This paper analyzes the features of the construction cost,running cost and output in the flood control and water drain section.The yearly benefits are random; the construction is the long-term acting and exhausted year by year.For making the produc function to be based on the actual cause and effect link,this paper advances to accumulate or average yearly bene fits to counteract the randomicity,then to calculate how much construction decrease in the corresponding period considering long-term acting.On this condition,the two kinds of the produce function are established.An example of the flood control and water drain produce function research in Jiangsu province is given.By the regression analysis the polynomial and power funce of the produce function are worked out.It shows that the flood control and water drain pay rate is very high after 1990 in Jiangsu province,and the running cost is more helpful to performance then construction cost.The accuracy and applicability of the method is verified by the example.