Objective:To investigate the effects of ultrafiltration membrane separation on the selenium-enriched Huangshan Gongju polysaccharides and the variations in the anti-oxidant and anti-inflamma-tory activities of different molecular weight fractions of polysaccharides. Methods:Ultrafiltration was employed to fractionate the polysaccharides extracted from selenium-enriched Huangshan Gongju,which were divided into two components of 100 kDa+polysaccharides and 100 kDa-polysaccharides. The antioxidant trials (hydroxyl radical scavenging capacity,DPPH scavenging capacity and total re-ducing capacity) and cell inflammation tests (NO detection kit and RT-qPCR methodology) were uti-lized to detect the antioxidant capacities and anti-inflammatory activities of polysaccharides obtained from before and after ultrafiltration. Results:The antioxidant activities of non-ultrafiltration polysac-charides (crude polysaccharide) and 100 kDa-polysaccharides were better than those of 100 kDa+polysaccharides. Both crude polysaccharides and ultrafiltration-treated polysaccharides had impacts on the inhibitory effects of IL-1β,IL-6 and TNF-α secretions. When polysaccharides concentration was 50 µg/mL,ultrafiltration-treated polysaccharides had better inhibitory effects on the IL-6 and TNF-α secretions. Conclusion:The 100 kDa-polysaccharides fraction demonstrated significant antioxidant ac-tivity. The 100 kDa+polysaccharides fraction could significantly reduce inflammatory responses in-duced by LPS in macrophages.