Abstract: An automatic gauge control(AGC) secondary loop control system was added to a monitor AGC system.A cascade control scheme was proposed for the AGC system based on the Smith prediction control model.Generalized predictive control(GPC) was used in the monitor AGC main control loop and a PID control strategy was applied to the secondary loop.Due to the secondary loop control system,disturbances added in the secondary loop are rejected,thus the influence of disturbances on the main control loop is weakened,the ability of rejecting disturbances is increased,and the control precision is improved.Simulation results show that the control strategy is effective and has a better control performance.