Abstract: The roll profile curves of the steel tube straighte ner has to comply with the full-contact principle, and thus conjugate curves forms between the roll and the pipe being straightened to ensure perfect enveloping and straightening result. Elaborated here in the paper are the following commonly-used three methods for calculation of the conjugate curves. The first is the manual plotting process as used at the early stage, and later developed as a computer-aided drawing process for determining the roll profile; The second is the computer-programmed multicirculating calculation method which includes the steps namely,finding a certain point in the straightening roll axis, and making the perpendicular tangent plane at this point so as to turn the calculation into a plane geometry issue, conducting calculation point by point with the computer to identify the points with their radium values conforming to the conditions as required,and then conducting the design also in a point by point way. The last one is a method that requests first deducing the functional relation formula for calculating the straightening roll radium,and then making direct design calculation. Thanks to the above mentioned methods,main issues concerning design of the straightening roll profile have been solved theoretically and practically.