Abstract: Lake eutrophication has a close relationship with the release of internal source. Decreasing the lake sediment resuspension caused by hydrodynamic effect can reduce the release of its endogenous pollutants. A numerical method is proposed to simulate the variation of flow velocity when it meets obstacles, and the decrease of flow velocity is investigated by different sizes of geocell. The results show that the water velocity has more significant decline when it passes the geocell in the lake bottom. The numerical results show the flow velocity above the geocell increases that behind the geocell decreases with the the height of geocell. The flow velocity in most areas behind the geocell can be reduced to “little action” or less. There are very limited effects for the flow velocity by increasing the length of geocell.