Abstract: In order to promote the realization of dual-carbon goal, the combination of hydropower system with hydrogen energy can improve the utilization rate of hydropower resources, reduce the cost of hydrogen production, and enhance the cleanliness of energy system to help China realize the energy transition. To this end, a two-layer planning model for an integrated water-hydrogen energy system considering hydro-electricity hydrogen production is constructed. In the upper layer, the goal is to minimize the system cost and improve the system hydrogen production and storage capacity as well as fuel cell performance. While in the lower level, the goal is to minimize load losses in daily operations to improve the utilization of all facilities in the integrated energy system. By considering the objectives at both levels together, the design and operation strategy of the system is optimized. Finally, an arithmetic analysis is carried out based on the actual operational data of a hydropower plant. The results show that the establishment of hydrogen facilities reduces the system cost by 19.08% and the abandoned water flow by 53.12%, which improves the utilization efficiency of hydropower plant, thus verifying the rationality and validity of the proposed model.