Abstract: Influenced by the cloud system and cold air around super typhoon "Lekima" No.201909, most of Yishusi region experienced heavy rain. Consequently, Yihe River suffered the worst flood since 1974. Affected by the opening of Zhangshan sluice, the runoff of Zhang-shu section and the inflow of Shuhe River, the measured historical maximum water level of Shuyang hydrological station of Xinyihe River is 11.31 m, which is 0.55 m higher than the historical maximum water level, and the maximum discharge is 5 900 m³/s. Based on the analysis of the water level and flow data of the control nodes of Xinyihe River during the influence of typhoon "Lekima" No.201909, this paper studies the evolution law of flood level and flow of Xinyihe River, analyzes the flood conveying capacity of Xinyihe River, and analyzes the flood propagation time of Xinyihe River under the current conditions. This study will provide scientific support for the accurate dispatching of water conservancy projects along Xinyihe River.