Objective This study was conducted to investigate the effects and mechanism of Moringa spp. polysaccharide extract on the occurrence and development of nonalcoholic fatty liver disease (NAFLD). Methods Fifty male rats were randomly divided into five groups (10 in each group):negative control group, model control group, low, medium and high dose group. From week 1, the negative control group and the model control group were given 10 ml/kg BW pure water by gavage once a day; each intervention group was given 10 ml/kg BW aqueous solution of Moringa spp. polysaccharide extract by gavage once a day until the 90th day. Blood samples were taken from the abdominal aorta and liver tissues after sacrifice. The total cholesterol (TC), triglyceride (TG), low-density lipoprotein (LDL), high-density lipoprotein (HDL), alanine aminotransferase (ALT), aspartate aminotransferase (ASL), superoxide dismutase (SOD) and malondialdehyde (MDA) of the serum were tested with the automatic biochemical analyzer. Serum interleukin 6 (IL-6), interleukin 1 (IL-1) and necrosis factor-α (TNF-α) were determined. Paraffin sections of liver tissue samples were stained with hematoxylin eosin. Results At the end of the experiment, there were statistically significant differences in body weight between the intervention group and the model control group(P<0.05). With the increase of dose, the serum index content(lipids, antioxidants, anti-inflammatory) in the intervention group was significantly different from that in the model control group (P<0.05), and tended to be the same as that in the negative control group. There also were statistically significant differences in LDL content between the high-dose group and the model control group (P<0.05). Microscopically, the model control group shown a variety of intrahepatic lesions, with deep lesions, severe hepatocyte steatosis. Although the hepatocytes in each intervention group were damaged to a certain degree, the types of lesion was less and less severe than that in the model control group. Conclusion The result of this study showed that Moringa spp. polysaccharide extract could significantly improve the lipid metabolism disorder in NAFLD, reduce the blood lipid level in rats, fight against the attack of oxygen free radicals, improve the inflammatory response and protect the liver. This protective effect may be achieved through antioxidant and anti-inflammatory pathways.