Abstract: Five operation schemes for comparison and selection were drawn up for the Chenglingji comprehensive hydroproject in this study. Based on the one and two-dimensional model for water-sediment in the middle and lower reaches of the Yangtze River, the water-sediment numerical model for the four inlets and four lower reaches of the Dongting Lake is established to study the influences of construction and operation of the Chenglingji sluice. The calculation and analysis results show that when the Chenlingji sluice is finished, the sedimentation of Dongling Lake is increasing with the increase of the water level, but the sedimentation in the Qilishan sluice downstream reaches is reducing and even scouring. The flood peak level of the Chenglingji sluice is rised by 0.03-0.05 m and the peak discharge is reduced by 142-330 m³/s. The flood peak level of the Hankou sluice has little change while the peak discharge is reduced by 93-141 m³/s. The operation scheme NO.3 as an option is finally selected for calculation. The calculation results show that 24 flood diversion areas of the Dongting Lake has increased by 0.1 million m³, the flood diversion discharge in the Honghu Lake is reduced by 140 million m³, and the flood diversion discharge in the vicinity of Wuhan and Poyang Lake are reduced by 0.94 billion m³ and 50.5 million m³ respectively.