In order to serve the construction and fine management of the ecological green development of the Yangtze River Delta integration demonstration area, ensure the safety of water resources in the demonstration area, the current situation and existing problems of water resources protection and cooperation in the demonstration area were clarified, and the new requirements of water resources protection cooperation mechanism were analyzed. Based on the practical experience of foreign typical cases of cross regional water resources protection cooperation, this paper puts forward three mechanisms based on the information sharing, connection of relevant standards, coordination and linkage of water resources protection in the demonstration area, and four supporting policies and measures, such as improving the legal guarantee in key areas, strengthening the joint monitoring of cross-border water bodies, strengthening joint law enforcement and supervision, and introducing a diversified market investment model. These policies and measures can further promote the fine management and protection of water resources in the demonstration area.