Abstract: The problem of sediment deposition at the tail reach of the Three Gorges Reservoir is a significant issue affecting navigation in the reservoir tail section. Based on the measured hydrological data and the fixed-section of the river in 2022, the sampling volume method was used to analyze and calculate the amount of erosion and deposition. Combined with the sediment reduction operations, the effect of sediment reduction operations at the tail of the Three Gorges Reservoir during the drawdown period was analyzed in depth. On this basis, the effects of inflow water and sediment conditions, water level variations in front of the dam, and previous sedimentation at the reservoir tail on the effectiveness of sediment reduction operations were discussed. The results show that: ① In 2022, sediment erosion in the main urban area of Chongqing was mainly concentrated during the drawdown period, with the erosion amount reaching 2.47 million m³, while sediment deposition occurred during the flood season and impoundment period, with the deposition amount of 1.01 million m³.② In 2022, the amounts of sediment erosion in the Jialing River reach, the reach above Chaotianmen of the Changjiang River, the reach below Chaotianmen of the Changjiang River, the reach from Tongluoxia to Lidukou, and the reach from Lidukou to Fuling were 130 000 m³, 170 000 m³, 1 080 000 m³, 6 060 000 m³, and 990 000 m³, respectively, accounting for 19%, 19%, 121%, 82%, and 84% of the sediment erosion during the drawdown period.③ From the correlation analysis among inflow water and sediment conditions, water level changes in front of the dam, previous erosion and deposition at reservoir tail, and the erosion and deposition in river channels, it was found that inflow water and sediment conditions are the most critical factors affecting the effectiveness of sediment reduction operations. The research results can provide an important reference for optimizing the operation strategy of the Three Gorges Reservoir and effectively mitigating the sediment deposition problem at reservoir tail.