This paper presents a practical basis of moveble bed model design via a practical example using moveable bed physical models was conducted. Model scales is determined based on the theory of sediment transport laws. 'Ihis research will take Cai - Nha Trang, Khanh Hoa province (the river segment from Xom Bong bridge to Tran Phu bridge) as an example illustrating the method of calculation and modeling. River segment with material is coarse sand and gravel, prototype average diameter matelials D50 equal to 0.00360 m. The model material as sand that made model river bed is natural sand material, model average diameter materials D50 equal to 0.00018 m is calculated at the scale of simulation. Velocity scale is determined by the ideal velocity. Model velocity simulation is the ideal velocity, liver evolution phenomenon is fully simulated. The paper concludes that: - When designing prototype river model with material is liver gravel, coarse sand, the flow velocity is quite large, the evolution model will ensure good river simulation conditions of sediment transport. For delta river, river bed material is fine sand, the design of moveble bed physical model can be fully simulated, but the model material used in the model river must be light weight materials. When the experiment, sediment transport out of the model has been collected at the tail gate, then compared the calculated results to adjust the amount of model sediment for subsequent experiment phases.