Abstract: To analyze the characteristics, impacts, and defense strategies related to the extreme rainstorm floods triggered by Typhoon "Gaemi" (No.3, 2024) entering into the Changjiang River Basin on July 26, 2024, this study systematically summarizes the joint operation measures and their implementation effectiveness of reservoir groups in the basin during the typhoon′s impact period (starting July 26), and comprehensively reviews and evaluates the defense and response measures deployed for this event.The results indicated that Typhoon "Gaemi" exhibited characteristics including a long duration, extensive impacted area, extreme rainfall intensity; it induced widespread heavy rainfall across multiple basins such as Poyang Lake, Dongting Lake, and Wujiang River, leading to floods exceeding the guaranteed water level in the main stem of the Xiangjiang River, and the Dongjiang Reservoir on Leishui River a tributary of Xiangjiang River experiencing a maximum inflow of approximately 200-year return period, highlighting exceptional extremity; consequently, the water level at the Lianhuatang Station on the Changjiang River main stem rose to the warning level on July 29, resulting in the formation of "2024 Changjiang River No.3 flood" in the middle reaches.Confronting these severe conditions, by jointly dispatching upper major reservoirs, we descended the water level at Chenglingji station in Dongting Lake by 0.20m and maintained the water level near the warning threshold, significantly alleviating flood control pressure across the Dongting Lake system.Based on the analysis, five key countermeasure recommendations are proposed: establishing a coordinated "monitoring-early warning-contingency response" linkage mechanism, enhancing flood response strategies for the residual typhoon circulation systems, optimizing collaborative dispatching models for flood control projects, developing an integrated technical support-field operations platform, advancing fundamental research on torrential rain and flood forecasting.These findings provide significant reference and guidance for responding to extreme rainstorm flood disasters triggered by strong typhoons.