The utility model relates to a device for generating perfect vortex light beam of fractional order, it produces the device to install the perfect vortex light beam of a fractional order, including a continuous wave laser, continuous wave laser emit light bundle's direction of advance is equipped with the speculum, and the light beam direction of advance after the speculum reflection is equipped with pinhole filter, convex lens I, the polarizer and beam splitting cube in proper order, light beam behind the beam splitting cube is divided into two bundles, a branch of reverberation that is wherein, a branch of transmitted light that is, be equipped with reflective spatial light modulator in the reverberation direction of advance, the light beam that produces after the reflection of reflective spatial light modulator is equipped with analyser, aperture diaphragm, convex lens II and CCD camera through behind the beam splitting cube in proper order in its direction of advance, the utility model discloses can realize the parameter perfect vortex light beam of the online fractional order that freely regulate and control in real time, but wide application in fields such as the manipulation of particle light, optical test.