Non-alcoholic fatty liver disease (NAFLD) is the most common type of liver disease worldwide. Recent studies have reported that oxymatrine (OMT), an active monomer isolated from Sophora flavescens Ait. (kushen), ameliorates NAFLD in rats. In order to explore the possible molecular mechanism involved, we used an NAFLD rat model with hyperlipidemia, which had been established by feeding a high‑fructose diet (HFD) for eight weeks, and the model rats were subsequently treated with OMT (80 mg/kg/day) for a further four weeks. We evaluated the expression of genes and proteins regulating fatty acid oxidation and lipid export in the liver using quantitative (q)PCR and western blot analysis. The NAFLD model rats developed dyslipidaemia, hepatic steatosis and insulin resistance (IR). OMT administration for four weeks reduced body weight gain and visceral fat weight, decreased serum triglyceride (TG), total cholesterol (TC), free fatty acid (FFA) and fasting serum insulin (FinS) levels and lowered liver TG contents. It also increased the glucose infusion rate (GIR), indicative of a reduction in IR. Moreover, OMT treatment markedly increased the mRNA and protein levels of peroxisome proliferator-activated receptor-α (PPARα), carnitine palmitoyltransferase 1A (CPT1A) and microsomal triglyceride transfer protein (MTTP). The beneficial effects of OMT were further confirmed by the observation of a decrease in lipid accumulation in the histology of the liver. Our results indicate that OMT may be used to treat NAFLD.