The invention provides a method for forming a liquid crystal alignment layer by undergoing a photopolymerization reaction. The method comprises the following steps of: injecting a liquid crystal alignment material and a negative liquid crystal material between a first substrate and a second substrate, wherein the liquid crystal alignment material comprises a monofunctional monomer and a multifunctional monomer; applying a voltage between the first substrate and the second substrate till the liquid crystal alignment material is deflected to a predetermined direction; and irradiating the liquidcrystal alignment material with ultraviolet light of which the wavelength is smaller than 310 nanometers till the liquid crystal alignment material forms a first alignment layer and a second alignment layer on the first substrate and the second substrate. The first alignment layer and the second alignment layer are obtained by inducing a polymerization reaction of the liquid crystal alignment material with ultraviolet light without using a rubbing process, so that the problems of impurity pollution, electrostatic interference and the like are solved.