Abstract: To assure the stableness of quality of the products, the computer control system adjusts the quantity of water, depending on the temperature of rod after rolling, in order to reach the predetermined temperature of rod's self-temper. This paper introduced the analysis of this computer control system which has been used in Tangshan Iron and steel mill, constitution of the hardware and software of this system, the inferring of mathematical model and the self-learning of model. The results of controlling were also given.