Abstract: The automatic gauge control (AGC) robust control for hot rolling strip is studied.To eliminate the influence of other variables on gauge control precision in the rolling process,a multivariable constrained control strategy based on H_∞/H₂ is brought forward.Firstly,norm H_∞ of the transfer function from the high-order unmodeled distur-bance to the control input is adopted as the index of robustness performance,and norm H₂ of the transfer function from constrained variables such as tension and looper to the output evaluating signals is adopted as the evaluating index of LQG (Linear Quadratic Gaussian) performance,so the constrained AGC model is constructed.Secondly,the H_∞/H₂ state feedback robust controller is designed,and the problem of constrained AGC control is transformed into the robust control problem in which certain system performance indexes under the model perturbations and the exoteric disturbance can be met.Finally,simulation results show the designed H_∞/H₂ controller is of robust control performance.