Abstract: In order to study the flow movement, bed evolution and sediment erosion and deposition of the natural rivers, a 3-D numerical model is established in body-fitling coordinates by a finite volume method, and SIMPLEC algorithm is used to calculate the 3-D velocity fields. The simulated results of the model are compared with the measured data. The findings indicate that the calculated results agree well with the measured data and reflect the 3- D flow characteristics in the natural meadering channels. The surface water particles will move towards the concave bank, while the bottom water particles will be towards the convex bank. It is shown that the model can be used to simulate the flow movement along the natural meadering channels.