A combined optimization method for searching the minimum disk weight and the best disk profile contour is provided which uses the random-walk method and the random-try method alternately. The whole disk profile contour can be linearized by linear segments

and thus the disk can be treated as a series of trapezoid-section ringlets. A subroutine for automatical generation of calculation sections is deveon loped. Taking the disk weight as objective function

the geometric parameters and the axial thickness of the ringlets as design variables

and the five stress criteria as constrains

we applied the combined optimization method to a practical disk and obtained a feasible point within 5-7 minutes on an IBM-PC. After one hour calculation the disk weight has been reduced 12.22%. It is proved that this method increases convergence rate obviously.