Step One embodiment of the invention using as the length divided by the length of the blades to the length ratio of the slab, the width expenditure divided by the width of the blades in the width of the slab to obtain the target crop length; After pre-assign a fixed value to the side cropping length of formula (1), wherein the length ratio, by substituting the width expenditure calculating a second thickness adjustment amount in the horizontal rolling mill when the first thickness of the horizontal rolling mill rate adjustment and pokchul rolling during pick-rolled step; Cropping side length = -α1 - (β1 × first thickness adjustment amount) + (γ1 thickness adjustment amount × 2) - (δ1 length × width ÷ expenditure ratio) + (ε1 × length ratio) + (ζ1 expenditure × width) + ψ1 ... formula (1), obtaining a length of the cropping dog adjustment amount using the first thickness and the second thickness adjustment amount; Calculating the length of the crop, minus the dog-shaped crop value (ΔC) at the target crop length; And if the cropping shape value is less than zero, the first thickness adjustment amount and the second depending on the thickness adjustment amount proceeds the rolling operation, wherein the crop the first thickness adjustment amount in the step b) if the shape value is more than "0" and to provide a second method of controlling the dog Plates made to re-obtain the two thicknesses Adjustment.