A rolling method in a rolling line, to obtain strip with a thickness varying from 0.7 mm to 20 mm, for steel which can be cast in the form of thin slabs with a thickness from 30 mm to 140 mm, the line includes a continuous casting device; a tunnel furnace for maintenance/equalization and possible heating; a rolling train having a roughing train and a finishing train; a rapid heating unit, with elements able to be selectively activated, interposed between the roughing train and the finishing train. For each lay-out of the rolling line, the position of the rapid heating unit which defines the number of stands which form the roughing train, disposed upstream of the unit, and the number of stands which form the finishing train, disposed downstream of the unit, is calculated as a function of the product of the thickness and speed of the thin slab.