We examined the methods of the nested flood simulation model focusing on the situation where dry beds are frequently present. New nested methods were developed to solve the error that caused by dry bed. The methods were applied to an uneven terrain of Bangladesh, and the methods have been validated by performing flooding simulations on the area. Method to pass the discharge and to pass the water level were applied to the trial simulation, and its results were compared with the result of the un-nested model with fine grids. Consequently, the results of the nested method using water level were superior on the viewpoint of flooded area, depth and volume. For the further research, consideration of the roughness depending on the grid size was suggested.