Abstract: The mechanism of water quantity increase entering the Taihu Lake from the Huxi sub-basin was explored. For the purpose, the coupled hydrology and hydrodynamic models of the Taihu Lake basin were established to simulate water stage variation of representative stations, as well as water quantity of important control lines. A knowledge graph was applied to study the flood drainage path. The simulation time series were divided into two periods; (i) 1990-2000:before integrated water resources management projects were in operation, and (ii) 2013-2018:after the Jiangnan canal upgrading, Meilianghu pump station, and city flood control projects were in operation. Three factors were identified to be responsible for the water quantity increase in the Taihu Lake from the Huxi sub-basin: increased precipitation, increase in the amount of water diverted from the Huxi and Wuchengxiyu sub-basins along the Yangtze River, and the Meiliang pump station and the Wuxi City flood control projects in operation. The results demonstrated that the annual average Taihu water stage increased by 0.05 m, and representative water stage of the river network increased by 0.02-0.16 m. The Wuxi City water stage increased significantly after the Meiliang pump station and Wuxi City flood control projects came into operation. Individually, the contribution of the three factors was almost equal, while their interactive effects were both synergistic and inhibitory, resulting in more intense flood contradiction for the Taihu Lake basin and its sub-basins.