Flood limit water level (FLWL) plays a major role in the trade -off between flood control and hydropower production of the multi-objective reservoirs. According to the prescribed operation rules of 2003-2006, the water level of the Three Gorges Reservoir (TGR) will be limited within the range of 134.9 m to 135.4 m in flood seasons. In this paper, the flood season of each year is divided into 12 intervals, each of which has a length of 10 days. Then, two mathematical models, one for simulation and the other for optimization, have been proposed together to obtain the optimal scheme of FLWL for each 10-day interval. By converting the chance-constrained multi-objective optimization model into a deterministic constrained single-objective one, the complexity of the problem has been greatly reduced and then an optimal scheme of FLWL for each 10 -day interval can be obtained. The results show that the optimal scheme can increase the hydropower production by 2.08% (2005) and 2.24 % (2006) without increasing the flood control risk.