Abstract: Using on-Line data of 1700mm hot-rolling Plant of Wuhan Iron & Steel Corp. and theoritical analysis, it is obtained that heat transfer coeffient is the key to the subject. After comparisions of seven different models, the Precisest model of heat transfer coefficient is proposed. On the basis of this model, a general program which can stimulate the laminar cooling process of Wuhan Iron & Steel Corporation is compiled, and higher precision is achieved.