Abstract: Based on the σ-coordinate transformation to fit the complicated boundary, the VOF to track the moving free surface and the SIMPLE algorithm, this paper proposes a vertical 2D unsteady flow and suspended material distribution model.It is efficiency, and able to simulate flow characteristic and transportation process of suspended material in reservoirs and rivers for the comparative uniform of the variation distribution in lateral direction.And it has an advantage over the other models with hydrostatic pressure or rigid-lid assumption.By the numerical verification of the schematic reservoir, the open-channel and trench, the model proves its reliability and validity in simulating vertical 2D flow and the concentration distribution of the suspended material.It can also give a scientific reference to flood dispatching, water pollution control and the optimization of the water diversion project, etc.