The impacts caused by the human activities such as sand mining upon the fluvial process in a river are the important problems to study in the river dynamics field. The Huangzhou reach in the middle Yangtze River was selected as a case study. Based on the data of the measured water and sediment series in the river basin, a 2-D mathematical model for water and sediment was established. The changing rules of the water level, flow velocities and water diversion ratio were analyzed, and the fluvial process in study area was simulated in three representative hydrological years. The simulated results show that the variation range of the water level and flow velocities will decrease with the increase of the flow discharge; moreover, the water diversion ratio is much more sensitive to the bankfull discharge, thus there will be an obvious increase in the water diversion ratio when the river reaches the bankfull discharge. Although there is a decrease in the sediment concentration after the operation of the Three Gorges reservoir, sand redeposition occurs obviously around the mining area with natural scouring and retrogradation around the riffle. The research results can provide a scientific reference for the feasibility study and planning of the sand mining in the similar rivers.