Based on the inverse design theory of pump impeller, a computer code was made in Fortran language to design the guide vane of high specific speed mixed-flow pump, with streamline iteration method to calculate the meridional velocity distribution, point-by-point integration method to draw the vane shape, conformal mapping method to thicken the vane and smooth the leading edge and trailing edge of the vane. In addition, the effects of the vane angle distribution and the position of vane outlet edge on the designed vane shape were discussed. This computer code could obviously increase the efficiency of design work and the accuracy of calculating results. And the data of the vane surface was complete, which is convenient for vane manufacturing by numerical control machine.