Abstract:Polysaccharide is the main bioactive component of Inonotus obliquus and has important functions and extensive medicinal value in anti-oxidation and immunity enhancement.In this paper，the process conditions of phosphorylation modification of I.obliquus polysaccharides were optimized by the single factor experiment and response surface methodology with the content of phosphate radicals in the polysaccharides of I.obliquus as the indicator to improve the biological activity of polysaccharides.The results showed that the optimal process conditions for phosphorylation modification of I.obliquus polysaccharides were as follows:the mass ratio of sodium tripolyphosphate to sodium trimetaphosphate of 6∶1，the reaction temperature of 75 ℃，the reaction time of 4 h，and pH8.6.The content of phosphate radicals in the modified I.obliquus polysaccharides was 9.58%.The findings of this study provide a reference basis for the development of phosphorylated derivatives of I.obliquus polysaccharides.