The invention relates to a printing sizing agent used for digital printing. The printing sizing agent is composed of lithium phosphate powder, asphalt, isopropyl phenyl diphenyl phosphate, methylaniline, camphor oil, eucalyptus oil, bronopol, trisodium phosphate, chlorothalonil, methylene diphenyl diisocyanate, modified phenolic resin, vinylidene chloride resin, trichloroethyl phosphate, 2-mercaptobenzothiazole, hexadecyl trimethyl ammonium bromide, camellia pollen, sodium iodoacetate, honey, potassium fluotitanate, zinc sulfide powder, a pearl powder, butyl stearate, methyl acetate, vinyl tris(beta-methoxyethoxy) silane, isopropylthioxanthone, isophoron, polyethylene glycol stearate, di-octadecyl dimethyl ammonium chloride, 10,10'-oxybis-phenoxarsine, and diazolidinyl urea. The printing sizing agent possesses excellent flame resistance, acid and alkali resistance, mildew resistance, and antibacterial performance, and product performance is improved.