Method for implementing steady control for elongation by using thickness control system

The invention discloses a method for adopting a thickness closed-loop control system to achieve the extensibility closed-loop control, which ensures that a current thickness control system can be used for timely measuring the material thickness H in of an inlet of a rolling mill and calculate the targeted setting value H out of a thickness gauge of an outlet of the rolling mill according to the formula H out = H in (1-r) and the set value r of the extensibility. The invention can adjust the outlet thickness to achieve the targeted extensibility through adjusting the rolling intensity, thus solving the problem of instable extensibility due to constant rolling intensity during the production process, and adopts the current control system to realize stable control of the extensibility with the variation ranged controlled at plus or minus 0.1 percent, thereby reducing the equipment investment and work intensity of an operator, caused by frequent change of technique parameters.