Automatic Tension Control (ATC) system is important for the cold tandem mill rolling of steel. Controller parameters must be adjusted continually according changing plant parameters to obtain better control performance. So it is very difficult to maintain strip tension within a tolerance with traditional PID controller. In this paper, the tension control systems are designed using variable parameters PID control on the basis of analyzing the dynamic tension control theory and the grey predictive control characteristic. Using the functional control can enhance the precision of the tension control. It is illustrated by simulation and Ansteel 1450mm mill production application results that the system dynamic response and robustness is advanced observably, and it has more favorable performance about restraining stochastic disturbances than conventional PID controller.