Reservoir storage capacity monitoring is the basis of reservoir operation. The relationship curves of reservoir water level-area and water level-capacity are the significant parameters of storage capacity calculation. With the long-term operation, both on the bottom and bank of the reservoir have erosion and deposition, causing the relationship of water level-area and level-storage changes, which leads to inaccuracy of reservoir storage capacity calculation with the original curves. It is costly to revise the curves of reservoir water level-area and water level-capacity by ground measurement termly. A coupled Method of Remote-sensing and Ground-monitoring of Reservoir Storage Capacity is proposed in this paper. Based on coupled data of satellite image of the reservoir water-area monitoring and the ground water-level monitoring on the same day, the relationship curves of reservoir water level-area and water level-capacity are updated, the calculation accuracy of reservoir storage capacity is improved. The Gangnan Reservoir is taken as an example for this research. 10 HJ-satellite images are used for revising the curve of reservoir water level-area and water level-capacity. The reservoir storage capacity differences between original and revised curves are analyzed and turned out to be reasonable.