The grain of strip steel can be turned to uniform． And the work hardening and inner stress can be eliminated by continuous
annealing line． So it is the key for improving steel’s mechanical properties． But in a real production process，the mechanism of continuous
annealing is complicated． The coupling operation parameters could change the characteristics of strip steel，and the detection of steel
hardness has a long time lag，which brings grate obstacle to improve steel quality． PLS is used to build the relationship between average
trajectory process and hardness． It can guarantee the safety of production process by realizing hardness prediction and process monitoring
timely． Simulations in real process shows the feasibility and effectiveness of the proposed method．