The invention relates to preparation method of antibacterial finishing agent of textile apply, belonging to textile assisting agent field. The antibacterial finishing agent for textile apply is prepared from zircoaluminate coupling agent, nanometer titanium dioxide, quaternary ammonium monomer, deionized water, and polymerization initiator synthetically react prepared; by mass, 7-11 parts of zircoaluminate coupling agent, 13-18 parts of nanometer titanium dioxide, 27-39 parts of quaternary ammonium monomer, 117-153 parts of deionized water, 0.8-1.3 parts of polymerization initiator. The method adopts the step of quaternary ammonium monomer after modification nanometer titanium dioxide ion surface grafting, restrict controls quaternary ammonium in basal body, compounds inorganic and organic antibacterial agent, overcomes the weaknesses that nanometer titanium dioxide light touch media loses antibacterial property at dim light and quaternary ammonium safety property appears poor and creates micro organism agent resistance, the finishing agent chemical stability stays poor, tolerates heat poor and more related weaknesses, helps achieves antibacterial agent safety, persistence, and efficiency property.