Abstract: Ultrafiltration method was used to isolate, purify and concentrate the Schisandra chinensis polysaccharide extract followed by 100 and 10ku ultrafiltration membranes.After further treatment, the yield proportion of pure polysaccharide fraction Sp1 (molecular weight above 100ku) was 6.31%, Sp2 (molecular weight 10～100ku) was 0.93%.The best operating pressures of 100, 10ku ultrafiltration were 0.207, 0.138MPa, the desired times of stable membrane flux were 30, 15min.Temperature had more effect on first ultrafiltration membrane flux.After polysaccharide extract was diluted more than three times, the impurity content of small molecules reduced to a low level.Compared with conventional chromatography separation of polysaccharides, ultrafiltration had a huge advantage in the processing rate, but slightly lower in the purity.