Abstract: Nonalcoholic fatty liver disease( NAFLD) is prevalent in patients with characteristics of metabolic syndrome. The main clinicopathological manifestations of NAFLD are fatty degeneration of liver parenchyma cells and fat storage,which can progress to liver cirrhosis and eventually lead to liver failure. Toll- like receptor 4( TLR4) signaling pathway is involved in the development and progression of NAFLD. At present,the role of TLR4 in the onset of NAFLD is highly valued by clinical doctors. This paper reviews the structure of TLR4,the composition of TLR4 signaling pathway,the regulation of TLR4 expression,the function of TLR4,and the relationship between TLR4 and NAFLD,suggesting that TLR4 signaling pathway is going to be an important research field in the treatment of NAFLD in the future.