Abstract: In recent years, the tidal flats at the Yangtze River estuary have been suffering from erosion risk with the sharp reduction of incoming sediment in the basin.In order to explore the evolution law and the variation characteristics of water and sediment in estuary tidal flat under the influence of human activities and natural environment, this paper takes Hengsha tidal flat as an example, and studied it by combining measured data with mathematical model.The measured data show that during 1998～2010 the flat was exposed to apparent deposition; while, from 2010 to 2019,it showed a slight scouring trend.The sand volume below-5 m and-2 m reached the maximum in 2010 and 2015,respectively, indicating the occurrence of the erosion in recent years.The simulated results show that both the hydrodynamics and the sediment concentrations in the shoal area show a continuous decreasing trend.In combination with the reality of continuous decrease in sediment supply, the tidal flat is supposed to be further eroded in the near future.Therefore, it is necessary to pay close attention to the changes in the estuary resources due to the variations of incoming water and sediment, and some corresponding countermeasures might be also considered to alleviate the situation.