The leakage Through the meshing rotors of a screw compressor is closely related to the screw intermeshing curves and leak triangles. In the past, the rotor profiles were designed by fitting the intermeshing curve and conjugate profile of one rotor to a predetermined profile of a coupled rotor. This paper investigates the possibility of seeking directly, in a converse manner, for a conjugate rotor profile on the basis of a given ideal intermeshing curve. We call it a converse method of rotor profile design. In this paper an integral equation is derived to form conjugate profiles from intermeshing curves with the illustrations of commonly used profiles; and the method of screw rotor profile conjugation with any arbitrary meching curves given in the form of discrete points is further expounded as an effective approach to the optimum design of screw gears.