OBJECTIVE： To optimize the decolorization condition for polysaccharide extract of Mongolian medicine Vicia amoena， and to establish the method for its extraction and content determination. METHODS： The water extract-alcohol precipitation was used to extract polysaccharide from Mongolian medicine V. amoena. Using decolorization rate as index， orthogonal test was designed to investigate the effects of the dosage of activated carbon， decolorization temperature， decolorization time on the decolorization of polysaccharide， so as to optimize the conditions for the decoloration of polysaccharide. Using glucose as control， phenol sulfuric acid method was adopted， and the content of polysaccharide in crude polysaccharide was determined by UV spectrophotometry at 490 nm. RESULTS： The optimal decoloration condition was as follows as actived carbon of 3％， decoloration time of 40 min， decoloration temperature of 60 ℃. On this basis， the average decolorization rate reached 19.77％（RSD＝1.85％，n＝3） by the verification test of the decoloration. The average extraction yield for the crude polysaccharide was 4.56％（RSD＝2.38％，n＝3）， of which the polysaccharide content was 1.98％（RSD＝2.18％，n＝4）. CONCLUSIONS： This experiment has relatively good reproducibility in polysaccharide yield； established method for content determination of polysaccharide is stable and feasible.