Abstract: In river model experiment, the section average flow velocity is different between distorted river model and normal model, the deviation degree of average flow velocity increases with the increase of distorted rate. The typical construction experiment shows that the section average flow velocity of distorted river model is faster than normal model; it is affected by distorted rate, boundary conditions and flow. The deviation degree of section average flow velocity is less 20% in boundary straight and flow smoothly, otherwise the opposite.