The Nanxian West-to-East Water Diversion Project and the Huahong Canal Connection Project were selected as typical cases, and the planned water system in the Dongting Lake area was optimized and evaluated based on connectivity indicators. The results show that the connectivity of the water system structure has declined under the planning conditions, indicating much room for optimization. Under the optimized conditions, the flow discharge of the west and middle branches of the Ouchi River in the Nanxian West-to-East Water Transfer Project increases up to 9.3 m3/s and 5.3 m3/s, and the hydrodynamic conditions are significantly improved. The discharge distribution coefficient at the outlet node of the optimized corridor is increased by 16.7%, effectively increasing the water delivery volume of the Zhongjiazui irrigated area. After the optimization, the water exchange cycle for increasing the storage capacity of the south and north lake group of the Huahong Canal Connection Project is reduced to 5 and 8 days, respectively, and correspondingly the water exchange efficiency is increased by 55.71% and 12.26%, respectively.