Abstract: A looper system possesses strong nonlinear, strong coupling, uncertain and multi-constrained features. For improving automatic gauge control accuracy and quality in hot strip mills, an appropriate mathematical model ought to be built so as to complete the decoupling control of loopers' height and tension system. According to the little signal theory, whole transferring functions of the looper system were presented by analyzing its coupling process and practical data. The control strategy of prediction for a linear model based on BP-PID was introduced to improve control effect and to decouple the looper system. The simulated results showed the effectiveness of this algorithrn and after decoupled, the loopers' control performance got much better.