Objective:To purify polysaccharides from Flammulina filiformis and evaluate the antioxi-dant activities.Methods:The purification parameters were optimized using hollow fiber ultrafiltration technology to isolate polysaccharides from F.filiformis.The antioxidant activity of polysaccharides was evaluated with Caenorhabditis elegans as a model.Results:Membrane pore size at 2 kDa and pressure at 0.08 MPa were optimal for purification.Ultrafiltration rate was stable within 50 minutes.High yield of polysaccharides was obtained under these conditions.Polysaccharides of 2~15 kDa,15~30 kDa,and above 30 kDa,were isolated by ethanol,respectively.And polysaccharides of 2~15 kDa dis-played the highest antioxidant activity.The maximum lifespan of nematodes treated with polysaccha-rides of 2~15 kDa was recorded as 12 days,which was twice longer than the control group.Conclu-sion:The polysaccharides from F.velutipes obtained by hollow fiber ultrafiltration technology had good antioxidant activity,which provided theoretical basis for the application of F.velutipes polysac-charides and could be used in the development of healthy functional food.