Abstract: The extraction and antioxidant activity of Tricholoma populinum polysaccharides(TPPs)were investigated in this study. Based on single factor experiments,the ultrasonic treating time,ultrasonic power and material to liquid ratio were analyzed and optimized by response surface methodology using TPPs yield as the response. Meanwhile,the antioxidant activities were evaluated by DPPH,hydroxyl and superoxide anion free radical scavenging capacity assays in vitro. The optimal extraction conditions were obtained as follows:extraction duration,27 min;ultrasonic power,410 W;and material to liquid ratio,1∶29 (g/mL).Under these conditions,the extraction yield of TPPs was 8.58%±0.02%. The TPPs showed potential antioxidant activities in a concentration-dependent manner,the DPPH,hydroxyl and superoxide anion free radical scavenging rates of TPPs were 52.25%,49.72% and 58.24% respectively at 0.05 mg/mL. The experimental results provide an experimental basis for studying the extraction and properties of TPPs.