This paper presents a new method called "intelligence sieve method" while gain enlightenment from the work style of a sieve, and makes the complicate optimization theory become more understandable, It presents a very simple but effective way of optimization and shows great robustness. Compare with several published papers, this method shows remarkable effect of optimization. The method has been used in the computer aided steel bar cutting system which has the functions of steel bar cutting, manufacturing, and stock managing, and shows remarkable effect.