The present invention provides a method and device of liquid crystal photo-alignment. The method comprises: providing a liquid crystal layer, liquid crystal layer doped with reactive monomer; under influence of an electric field, using radiation light to irradiate on liquid crystal layer to trigger polymerization of monomers to achieve the photo-alignment of liquid crystal layer; wherein polymerization of monomers comprising a first stage and a second stage following the first stage, the radiation light having a first illumination in the first stage and having a second illumination in the second stage, and the first illumination being less than the second illumination. The method and device of liquid crystal photo-alignment of the present invention improves the stability and uniformity of the photo-alignment of the liquid crystal, and satisfy the photo-alignment reaction speed as well as effectively avoid the light leakage caused by macromolecular effect.