The invention relates to a method for configuring the shape of a supporting roll of a four-high mill and the shape of a working roll thereof, belonging to the technical field of steel rolling. According to three types of width specifications of band steel which are most rolled by hot-rolling band steel production line, sixth-power polynomial supporting roll shape technology and second-power working roll shape curve are used for configuration so as to lead the contact length of the supporting roll and the working roll and the width of the rolled band steel to be fit. The method has the advantages of eliminating hazardous contact areas in which the parts of the two ends of the supporting roll with the flat roll shape and the working roll expand out of the edge of the band steel to generate large deflection and deformation, solving the problems that the stress concentration of the edges of the supporting roll and the working roll in a hot continuous mill for wide band steel causes stripping and the mill roll with the flat roll shape has large wearing capacity and is not even, reducing the consumption of the mill rill, saving energy, reducing consumption and reducing cost for rolling steel; and by the technical configuration of R2 working roll shape and the supporting roll shape, the invention solves the plate-shape problems that the middle blank generates negative convexity and the wedge shape is large, and improves the control precision of the shape of hot-rolled band steel.