Abstract: The antioxidant stability of crude polysaccharide was evaluated by measuring the scavenging capacity against hydroxyl free radicals under various conditions of pH, temperature, metal ions and illumination.The results indicated that the eliminating ratios of hydroxyl free radicals under the conditions of pH7 and temperature 80℃ were the highest.Moreover, it was not obvious to have metal ions such as Na+, K+, Ca2+ for the scavenging capacity.So the crude polysaccharide was relatively stable in the presence of metal ions such as Na+, K+, Ca2+ and acid, while poor antioxidant stability of crude polysaccharide was observed in the presence of alkali, light or heat.This research was a preliminary one on the antioxidant stability of crude polysaccharide, which provided some information for further application development of the crude polysaccharides as antioxidants.