Abstract: Standard for Rank Classification and Flood Protection Criteria of Water and Hydropower Projects is the most important and basic design standard in water conservancy industry and the new version has been revised and released in 2017. This paper summarizes the standards for rank classification and flood protection criteria in different periods and the revision necessity in 2017, and the general thoughts and the key technical issues of the revision are discussed. In the revision, Standard for Rank Classification and Flood Protection Criteria of Water and Hydropower Projects is improved, in which a general architecture is determined as follow, firstly the project grade, secondly the structure grade, thirdly the flood criteria according the structure grade. In addition, the reasonable division approach and criteria are studied and determined, including project classification approach, grade classification indexes and flood criteria. Furthermore, it supplements correlative standards on super-high dams and cascade reservoirs according to the development level of the industry. This research summarizes the experiences and deficiencies in the revision of Standard for Rank Classification and Flood Protection Criteria of Water and Hydropower Projects to promote its application and continuous improvement.