The invention discloses a 
citric acid-
chitosan-modified anticoagulation 
polyurethane blood 
dialysis membrane and a preparation method thereof. The membrane is of a hollow fibrous structure, and the inner surface and outer surface are dense cortical 
layers, and the middle is a porous supporting layer, so that the blood 
dialysis membrane is high in permeability and separating property and 
antibacterial property; the inner 
diameter is 160 to 250mu m; the 
membrane thickness is 30 to 50 mu m, and the 
ultrafiltration coefficient is 7.0 to 60 ml / m<2>.h.mmHg; 
citric acid-
chitosan-modified anticoagulation 
polyurethane is taken as membrane materials, and in membrane solution, the percentage 
mass content of the modified anticoagulation 
polyurethane is 15 to 30%, and the percentage 
mass content of a 
solvent is 70 to 85%, and the blood 
dialysis membrane is prepared by using a nonsolvent induced phase 
separation method. The preparation process of the dialysis membrane is simple and easy to control, and the prepared membrane has good 
anticoagulant activity, 
biocompatibility and 
antibacterial property, and the clearance rates of 
urea, beta2-microglobulin and 
albumin are respectively 55 to 80%, 48 to 60%, and 2.5 to 9%, and the rate of resisting 
pathogenic escherichia coli is 99%.