Abstract: Afterthe impoundment of the Three Gorges Reservoir, major period of erosion in the tail reaches has gradually changed from the period of September to October undernatural condition to fluctuating period of April to June. In order to increase the erosion in fluctuating period and reduce the sedimentation in local reaches which may block navigation. Regulations to reduce sedimentation in the tail area of the reservoir are presented based on one-dimensional unsteady flow-sediment model. It is shown that better erosion effects can be achieved by controlling the stage in front of the dam within the range of 160~162m and the stage fall in a day within 0.4~0.6m in the condition of Cuntan flow about 7000m3/s. According to these results, in-situ experiments were successfully completed in the fluctuating periods of 2012 and 2013. Analysis of the measured data indicate that the total erosion in the tail reaches is 2.411 and 4.413 million m3 during the two years' regulation periods respectively, a good effect in sedimentation reduction. The measured data in 2012 were used to validate the mathematical model. A comparison with the calculations shows that the model is effective in qualitative calculation of erosion and deposition and basically reasonable in quantities for most of the reaches.