The present study was designed to observe the protection of Grateloupia filicina polysaccharide (GFP) against hepatotoxicity induced by Dioscorea bulbifera L in mice and its underlying mechanism. GFP was intragastrically (ig) given to mice at various doses. After 6 days, the mice were treated with ethyl acetate extract of Dioscorea bulbifera L (EF, ig). Serum levels of alanine/aspartate aminotransferase (ALT/AST), alkaline phosphatase (ALP), total bilirubin (TB) were measured, and liver histological evaluation was conducted. Furthermore, reductions of liver glutathione (GSH) amount and glutamate cysteine ligase (GCL) activity were tested. The expressions of GCL-c, GCL-m, and HO-1 (heme oxygenase-1) in liver were observed by Western-blot. The results showed that GFP (600 mg x kg(-1)) decreased EF-induced the increase of serum ALT, AST and TB, and GFP (400, 600 mg x kg(-1)) inhibited EF-induced the increase of serum ALP. Liver histological evaluation showed that the liver injury induced by EF was relieved after treated with GFP. GFP further increased liver GSH amount and reversed EF-induced the decrease of GCL activity. The Western-blot result showed that GFP augmented EF-induced the increase of HO-1, and reversed EF-induced the decrease of GCL-c. In conclusion, GFP can act against the oxidative stress liver injury induced by Dioscorea bulbifera L in mice.