Abstract: A nonalcoholic fatty liver(NAFLD)rat model was established by fat emulsion. After modeling,the Tremella polysaccharides group(TP)was intragastrically administered with Tremella polysaccharides of 200 mg/kg,the control group and the model group were intragastrically administered with water for 28 days. At the end of administering,biochemical analyzer was used to measure serum total cholesterol(TC),triglyceride(TG),low density lipoprotein cholesterol(LDL-c),high-density lipoprotein cholesterol(HDL-c),alanine aminotransferase(ALT),aspartate aminotransferase(AST)and alkaline phosphatase(ALP). Hematoxylin-eosin staining was used to observe the pathological changes of liver tissue. Gas chromatography-mass spectrometry technology was used to obtain the metabolic fingerprints of liver homogenate samples from control group,NAFLD group and Tremella polysaccharides group. The pattern identification method combined with metabolic network database was used to determine the biomarkers in order to explore the metabolomics mechanism of Tremella polysaccharides on NAFLD rats. The results showed that Tremella polysaccharides could decrease the levels of serum TC,TG,LDL-c,ALT,AST and ALP,increase the level of HDL-c on NAFLD rats. Furthermore,Tremella polysaccharides could reduce the liver fat accumulation and decrease the degree of fatty degeneration in liver of NAFLD rats. Tremella polysaccharides showed obvious hepatoprotective effect on NAFLD rats. The mechanism was related to regulate 12 biomarkers(malic acid,sorbitol,glycine,D-glucuronic acid,fumaric acid,D-glucose,citric acid,D-ribose,propionic acid,suberic acid,and cis-aconitic acid)and 6 major metabolic pathways(synthesis and degradation of ketone bodies,glyoxylate and dicarboxylate metabolism,ascorbate and aldarate metabolism,glycine,serine and threonine metabolism,and TCA cycle)back to normal levels.