A vortex light beam device comprising: a metal reflector (101), a low refractive index layer (102), and a plurality of elliptical dielectric units (103). The low refractive index layer (102) covers the metal reflector (101), and the plurality of elliptical dielectric units (103) are embedded in the low refractive index layer (102). The plurality of elliptical dielectric units (103) are distributed in an array format, and the straight lines at the long axis of the plurality of elliptical dielectric units (103) are parallel or coincident. The thickness of the plurality of elliptical dielectric units (103) is the same, and the thickness of the low refractive index layer (102) is greater than the thickness of the elliptical dielectric units (103). The outer surface of each elliptical dielectric unit (103) is flush with the outer surface of the low refractive index layer (102), and the outer surface of the elliptical dielectric units (103) and the outer surface of the low refractive index layer (102) is the surface furthest from the metal reflector (101); the refractive index of the low refractive index layer (102) is lower than the refractive index of the elliptical dielectric units (103). Also disclosed are a preparation method for the vortex light beam device and a method for generating a vortex light beam.