A photoalignment film derived from photosensitive self-assembled monolayer with a p-phenylenediacrylate group is reported. The precursor film was prepared by self-assembled reaction of chemical adsorption, and then the film was irradiated by linearly polarized ultraviolet light. The photoalignment film induces nematic liquid crystal to align homogeneously, and the alignment direction of the liquid crystal molecules is perpendicular to the polarized direction of incident ultraviolet light. By variation of the length of the alkane chain and the different functional group at its terminus, the self-assembled photoalignment films with different polarity were prepared and determined. The film with n-alkyl benzene moieties showed better alignment performance than the others.