Abstract: In view of the flood control task undertaken by the Three Gorges Reservoir, this paper analyzes the reservoir capacity release conditions of Three Gorges Reservoir for Chenglingji-oriented flood control regulation from two aspects:① the flood characteristics of the Yangtze River Basin and Dongting Lake water system, ②the flood control standard in the area near Chenglingji reach and flood control regulation mode of Three Gorges Reservoir oriented to Chenglingji. In the year of a basin-wide big flood occurrence, Three Gorges Reservoir will operate at a higher water level for a long-time to intercept the flood and use greater flood control capacity. If there is no big flood in Dongting lake water system, the reservoir capacity for Chenglingji-oriented flood control of Three Gorges Reservoir could be released. In the year of no basin-wide big flood, there is usually no big flood occurrence in Dongting lake water system after July 20th，in addition, Dongting Lake itself has large flood regulating capacity and its flood control safe can be ensued, so the operation water level of TGP reservoir can be gradually raised to the level of 155 meters from August 1st. The above suggested operation plan will enhance the integrated efficiency of water resources utilization, reduce the impact of Three Gorges Reservoir impoundment on the lake water level during water storage period, insure the security of water supplement in the lake area. The analysis results can guide scientific operation of the Three Gorges Reservoir.