Under the constraint of the strictest water resources management system ,the paper followed the principles of rationality, scientificity to establish “Three Red Lines” as a water safety indicator system,and proposed the fuzzy set pair evaluation model of water safety based on information entropy, and then determined the level of water safety assessment by calculating the fuzzy relation degree and the criterion of setting confidence. Finally, the paper combined an empirical study of water safety evaluation for 8 administrative regions of Qinghai Providence and compared the results with that of grey clustering and analytic hierarchy process.The research shows that the overall water safety level of Qinghai Province is grade Ⅳ,and is more relatively unsafe state.The situation is not optimistic.The results given by fuzzy set pair analysis are consistent with the results by the other two methods. The method is easy to be programed and has certain application value for water safety assessment.