The invention discloses a blood dialysis membrane and a preparation method thereof. The blood dialysis membrane is mainly prepared from the following raw materials by mass: 21-55 parts of collagen, 16-42 parts of silk protein, 8-19 parts of fibroin, 7-15 parts of sericin, 11-25 parts of cellulose, 2-15 parts of polyethersulfone, 2-7 parts of sulfonated polyethersulfone, 7-22 parts of heparin, 3-13 parts of lysine, 4-11 parts of cellulose acetate, 9-22 parts of methyl acrylate, 14-29 parts of polyacrylamide, 2-11 parts of sodium bicarbonate, and 32-60 parts of deionized water. Compared with the prior art, the blood dialysis membrane provided by the invention has the advantages that: (1) the blood dialysis membrane prepared by the invention has good permeability to a to-be-removed solute, and also has high interception rate to protein in blood; (2) the blood dialysis membrane prepared by the invention has good bacteria and virus obstruction effect, and also has good water permeability; (3) the blood dialysis membrane prepared by the invention has does not cause blood coagulation reaction and pyrogen reaction; and (4) the blood dialysis membrane prepared by the invention has good compatibility with blood, and has moderate mechanical strength.