Water-saving evaluation is the main fulcrum to implement the strictest water resources management system in China. Water-saving evaluation based on the existing guidelines has shortcomings: evaluation indicators are independent from each other, and have different degrees of influence. We studied on the evaluation index system for enterprise and the evaluation method on the basis of the existing evaluation indicators. A total of 24 indicators were selected, by filtering those can truly reflect the water intake, water utilization, water deprivation, and drainage of the enterprise, as well as building a 2-layer criterion of management and technology. Analytic hierarchy process (AHP) was used to calculate the weight of each index. Among them, the weight of decline rate of water withdrawal per unit, product with repeated utilization, and decline rate of water withdrawal per ten thousand yuan of output are larger, which is 0.27, 0.15, and 0.15, respectively. The evaluation index system was used on a certain iron and steel enterprise. The aim of this study is to construct a set of index system with different weights for the water-saving evaluation of enterprises. The rationality of the evaluation results can be verified between the index layers. This work may provide some new ideas for water saving evaluation in the future.