Background: Chronic liver disease (CLD) is a global epidemic chronic disease, which has always been a threat to human health. This study aimed to investigate the effects and mechanism of icariin (ICA) on highfat diet-induced nonalcoholic fatty liver disease (NAFLD).Methods: Thirty Sprague Dawley rats were divided into five equal groups: the control, NAFLD, NAFLD + ICA 25 mg/kg, NAFLD + ICA 50 mg/kg, and NAFLD + ICA 75 mg/kg groups. A rat model of NAFLD was constructed by feeding rats a high-fat diet and then treating them with 25, 50, or 75 mg/kg of ICA by gavage.HepG2 cells were cultured and treated with 1 mM FFA (oleic and palmitic acids, 2:1) and ICA at 20, 40, or 80 μM for 24 h. Later, the HepG2 cells were transfected with miR-206 inhibitor or its negative inhibitor.The serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), total bilirubin (TBil), triglyceride (TG), total cholesterol (TC), and low-and high-density cholesterol (HDL-C) were measured in each cell group with an automatic biochemical analyzer. Liver injury and lipid deposition were observed by hematoxylin-eosin and oil red O staining. Interleukin (IL)-1β, IL-12, and IL-6 levels in liver tissues and cell supernatants were measured by enzyme-linked immunosorbent assay (ELISA). Additionally, the MTT [3-(4,5-dimethylthiazol)-2,5-diphenyltetrazolium bromide] assay was applied to measure cell proliferation, and quantificational reverse transcription-polymerase chain reaction (qRT-PCR) was performed to detect miR-206 expression. Western blot was used to determine nuclear factor kappa-B (NF-κB) and mitogenactivated protein kinase (MAPK) pathway-related proteins in liver and cells.Results: ICA-treated rats had reduced levels of ALT, AST, TBil, TG, TC, and low-density cholesterol (LDL-C) but increased levels of HDL-C compared to rats in the NAFLD group. It also reduced IL-1β, IL-12, and IL-6 levels in tissues and cells in a dose-dependent manner, and acted in reducing the expression of MAPK and NF-κB-related proteins in the livers of NAFLD rats. ICA was not cytotoxic and increased miR-206 expression in tissues and cells.Conclusions: ICA can alleviate NAFLD by up-regulating miR-206 to mediate the NF-κB and MAPK pathways.