Abstract: To evaluate the effects of fermentation on the antioxidant activity and irritancy of Polygonatum sibiricum,theantioxidant activity was evaluated by DPPH free radical scavenging rate,iron ion reducing power and protective effect on human umbilical vein endothelial cells(HUVEC)by hydrogen peroxide damage,and irritation was evaluated by SIRC cell short exposure method. The relationship between the changes of main active ingredient contents of the Polygonatum sibiricum obtained by the fermentation method and the traditional processing method(steaming method,wine production method)and its antioxidant activity and irritancy were preliminarily investigated. The results indicated that the fermentation method had prominent effect on increasing antioxidant activities and declining irritation of Polygonatum sibiricum. The viability of HUVEC cells increased to 78.13%±4.25% from 54.66±4.12% of model set after being treated with fermented Polygonatum sibiricum,and the viability of SIRC cell treated with the fermented one also rised from 68.55%±5.23% of raw sample to 92.6%±3.55%. The increasing in the activity of fermented products was mainly related to the change of polysaccharides. In the fermented products,the contents of the total polysaccharide were reduced from(141.44±2.25) mg/g_{raw material} to(121.84±2.94) mg/g_{raw material} and the monosaccharide components such as mannose and galactose were decreased. However,the contents of rhamnose increased significantly(P<0.05)from(2.90±0.01) mg/g_solids to(20.92±0.00) mg/g_solids,and the contents of fucose was also increased from(0.77±0.00) mg/g_solids to(4.78±0.01) mg/g_solids with changes of the ratio of monosaccharides.The irritation was more affected by the component of saponins,and the decreasing in irritation after fermentation was related to the reduced significantly(P<0.05)contents of total saponins. In summary,fermentation could induce the transformation of active components,then improve the bioactivities and irritation of the Polygonatum sibiricum,which had important practical application value.