Abstract: Sediment deposition not only occupies the storage capacity, but also releases pollutants into the water body. In this study, the sediment distribution in the Tangpu reservoir has been investigated based on MIKE 21 software. The research results show that the sediment distribution is uneven in the reservoir. At the zone of the reservoir entrance, sediment deposition is not severe, and sediment erosion even occurs at sone places. In the centre of the reservoir there is significant sediments deposition, and the maximum simulated thickness of sediment deposition is about 30 cm, and the minimum thickness is about 12 cm, which is close to that of the dam front. Sediment sampling results are consistent with the simulation results. It means that the model can be used to simulate the sediment distribution along the Tangpu reservoir reasonably. The simulation results have some reference values for the control of internal source pollution in the Tangpu reservoir.