The invention discloses antibacterial medical drainage polyurethane foam and a preparation method thereof. The antibacterial medical drainage polyurethane foam is prepared from the following raw materials in parts by weight: 100 parts of polyether polyol, 1.2 to 3.5 parts of an organic silicon foam stabilizer, 1 to 15 parts of a foaming agent, 0.1 to 1 part of tannic acid, 0.1 to 0.6 part of imidazolidinyl urea, 0.5 to 6 parts of sulfadiazine silver, 1 to 10 parts of chitosan, 35 to 65 parts of toluene diisocyanate, 0.1 to 0.5 part of amine catalyst, 0.10 to 0.70 part of a zinc catalyst and 1 to 6 parts of water. According to the antibacterial polyurethane foam disclosed by the invention, various antibacterial agents such as chitosan, tannic acid and sulfadiazine silver are selected, oxygen active sites are provided for the polyurethane foam, so the polyurethane foam has an antibacterial property, meanwhile, the polyurethane foam has excellent biocompatibility, no teratogenic effect, no anaphylactic reaction and excellent anticoagulant performance; a toxicity test result show that the polyurethane foam meets medical requirements; and the te polyurethane foam has the advantages of excellent toughness and elasticity, good processability, various processing modes and the like.