Abstract: Dictyophora indusiata polysaccharides(DPs)and various fractions were further graded by ethanol precipitation. Both of them were used to evaluation its prebiotic efficacy by in vitro proliferation test of Bifidobacterium adolescentis. The results showed that after hydrolysis for 4 h in α-amylase solution,the hydrolysis degree of 20%,40%,50% and 60% of DIP were 9.10%,8.02%,8.88% and 11.67%,respectively. Compared with the control group,the difference in the degree of hydrolysis(13.15%)was significant(P<0.05). The difference between the 80% fractionated alcohol precipitation fraction and unfractionated alcohol precipitation fraction was not significant with control group(P>0.05). After hydrolysis for 6 h in simulated gastric juice,the hydrolysis degree of 20%,40% and 50% of DIP were 17.30%,14.52% and 9.61%,respectively,which was significantly different from the control of inulin(degree of hydrolysis 5.72%)(P<0.05). 60%,80% fractionated alcohol precipitation fraction and ungraded alcohol precipitation fragment hydrolysis degree was not significantly different from the control group(P>0.05). With the increasing of DIP,the concentration of Bifidobacterium adolescentis increased first and then decreased. Compared with the 80% alcohol precipitation fragment of DIP and the unclassified polysaccharides(both showed similar effects during the fermentation time of 20 h),the proliferation in vitro and pH of Bifidobacterium adolescentis was significantly lower than that of inulin group(P<0.05),and. Compared with raw DIP,different DIP fractions by graded ethanol precipitation displayed certain difference on growth and acidifying activity of Bifidobacterium adolescentis. The proliferation effect and the hydrolysis resistance of DIP increased with the ethanol concentration increasing. Unclassified polysaccharides components also have ability to proliferate against Bifidobacterium adolescentis and may be a potential prebiotics.