The designed floodwater storage frequency and storage pattern are main thresholds for flood management and regional social-economic development in flood retention areas of China's river basins. Under the backgrounds of "Integrated Flood Management" and "Sustainable development", this paper focused on the optimal developing approaches in China's flood retention areas. Based on different designed floodwater storage frequencies in detention areas, 3 development scenarios, as status quo, proportionally wetland restoration and proportionally reservoir-shaping, were first established within 35 years. Meanwhile, multi-objective evaluation index system was built consisting of flood mitigation, social-economic development and ecological benefits. Finally, according to Data Envelopment Analysis (DEA), the optimal approaches for different flood retention areas were identified and discussed. DEA model results indicated that proportionally wetland restoration was the optimal approach for 70% flood retention areas in China and "flood period 50" of designed frequency for floodwater storage was the boundary of various flood retention areas-if the designed floodwater storage frequency of a flood retention area was lower than "flood period 50", proportionally wetland restoration was its optimal developing way, while, if higher than "flood period 50", maintaining its status quo was the optimal way. The research findings could provide valuable suggestions and decision-making support for flood management and sustainable development in flood retention areas.