The process of strip rolling is a multivariable process control system.Product quality is influenced by couplings between useful input and output and between interference input and output.By use of a decoupling controller and a feedforward compensator ,the system is decoupled and the interference caused by the disturbance in slab thickness is depressed.The practice showed that the decoupling controller and the compensator have good availability ensuring improved AGC and ASC in combination.