Abstract: The extraction of bioactive polysaccharide in Semen vaccaria was studied in this paper. The water extract and alcohol precipitate method was used for the extraction of polysaccharides and was optimized by single factor and orthogonal experiments. The polysaccharide content was determined by phenol-sulfuric acid method after enzymatic degradation. The optimum extraction condition was obtained as follows:100℃, extract for three times with 2 hours and water-material ratio of 10∶1 (mL/g) for each time. Under the optimal conditions, the polysaccharide yield was 29.32%. The polysaccharide yield for the fried Semen vaccaria was 22.15%.