Li+-doped HoPO4 powders with a pure tetragonal phase are successfully synthesized by the co-precipitation method. It exhibits an obvious color change under sunlight and tri-phosphor fluorescent light illumination. The introduction of Li+ ions into HoPO4 can further enhance its photochromic property effectively. The doped Li+ ions induce changes in the crystal structure. The spectral characteristics and thus photochromic properties of HoPO4 are explored. The improved HoPO4 powder, when used as a photochromic material, has wide-ranging prospects in security, decoration, and other applications.