The invention relates to a fabric printing sizing agent used for digital printing. The fabric printing sizing agent is prepared from the following components: polyethylene, polyester-urethane resin, o-cresol formaldehyde epoxy resin, citronellyl formate, polypropylene ethylene glycol, polyether silicone oil, carbomer resin, rosemary essential oil, Baijunduo, salicylanilide, cecropin, sodium dehydroacetate, vanadium pentoxide powder, antimony pentoxide powder, cellulose, rubber particles, bismuth nitrate powder, candelilla wax, zinc oxide, chimney soot, trichloroethyl phosphate, polybenzimidazole imide, nano-magnesium hydroxide, polyethylene wax, hydroxypropyl starch ether, hydroxypropyl methyl cellulose, hydroabietyl alcohol, nonylphenol polyoxyethylene ether, glycerol triacetate and trimethylolpropane trimethylacrylate. The product has excellent flame retardance, acid-base resistance, mildew resistance and antibacterial properties and has the effect of improving the product properties.