Tetrastigma hemsleyanum Diels et Gilg, a rare herbal plant native to China, possesses high medicinal value. More researches have focused on the flavones in the tubers of Tetrastigma hemsleyanum whereas polysaccharides attract few attentions. In this study, a purified polysaccharide (TTP-1) with the average molecular weights of 478.33 kDa was extracted from Tetrastigma hemsleyanum and conducted multiple analysis to identify its structural information. In vitro, TTP-1 could suppress the inflammation, cytotoxicity, genotoxicity, mitochondrial dysfunction and oxidative damage induced by LPS in RAW264.7 cells. Meanwhile, TTP-1 could attenuate inflammation via COX-2, iNOS, MAPKs pathways and ameliorate oxidative damage through Nrf2-Keap1, Sirt1-FoxO1 pathways in RAW264.7 cells. In vivo, the inflammation induced by LPS triggered the suppression of survival ratio and growing development, as well as the restrain of athletic ability in Caenorhabditis elegans. The treatment of TTP-1 reversed the situation induced by LPS. In a word, TTP-1 could ameliorate LPS-induced inflammation both in vitro and in vivo.