Abstract: Based on the Finite-Volume Coastal Ocean Numerical Model(FVCOM), a hydrodynamic model was established to study the tides and suspend sediments in the Minjiang River Estuary and its adjacent sea areas.The model results were found in good agreement with tide gauge and current data, and the model simulated the hydrodynamics well.The numerical model was employed to simulate the diffusion of suspended sediment caused by different sand mining schemes in B6 area.The starting time of sand mining was set as the rising and falling time.The maximum influence ranges of suspended sediment were analyzed and the contour maps of 10 mg/L, 50 mg/L and 100 mg/L suspended sediment were presented.The results showed that suspended sediment had little impact on the sensitive protection targets of the surrounding marine environment.