Abstract:  This paper studied the optimum preparation procedure for extraction and septeration of the Usnea subfloridana polysaccharide. The optimum extraction conditions of Subfloridana polysaccharide are: water 200ml, Usnea subfloridana 4g, extracting-temperature 70～80℃, repeated-times 3 and extracting-time 2h. The results showed that the variance of the factor reapeated-times assumes statistical significance, whereas the extracting-temperature is not statistically significant. A one-factor test results indicated that the optimum conditions of precipitating polysaccharide with 70% alcohol, and removing proteins with sevage agent to gain gratifying effictiveness are as follows: volume ratio 2:1, oscillation-time 30min and repeated times 7 with polysaccharide yield 6.86% and total sugar content 76%.

Key words:  , Usnea subfloridana； polysaccharide； experiment extration methodology； optimization；