Filter method is used to measure the bacteriostatic circle. With bacteria and fungi as test stranins,inhibition experiments using polysaccharide of different concentrations from Pholiota dinghuensis Bi were carried out.Chemical method was used to measure and analyse in vitro antioxidant activity of polysaccharide from Pholiota dinghuensis Bi,with Vc and EDTA-2Na as positive control respectively. The results showed that polysaccharide from Pholiota dinghuensis Bi has obviously inhibitory effect on gram-positive bacteria. The diameter of antibacterial circle for Bacillus subtilis and Staphylococcus aureus were 7. 85 mg / mL and 7. 91 mg / mL respectively. And with the increasing concentration of polysaccharides,the inhibitory effect was stronger. However,it was not obvious for inhibition of gram-negative bacteria and fungi. Polysaccharide from Pholiota dinghuensis Bi could remove DPPH·free radicals and chelate ferrous ion( Fe2 +) and remove hydroxyl radicals and had certain of in vitro antioxidant effect.