Abstract: By applying the numerical method, presented by J. S. Montes, for solving inverse weir problems, this paper puts forward a method of designing control weir for hydraulic model in accordance with a given head-discharge equation almost automatically. The method may be applied to a hydraulic model test. The result of application shows that the method is efficient, simple and practicable. Relative errors of water level between model and prototype data equal 2%*.5%.