Abstract: Non-alcoholic fatty liver disease (NAFLD) has become the most common chronic liver disease in China, and its incidence is increasing year by year. At present, the specific pathogenesis is not clear, and the "multiple hit" theory based on the "second hit" theory is widely recognized, which also provides a more accurate explanation for the pathogenesis of NAFLD. Based on the related research in recent years, this article mainly discusses the pathogenesis of NAFLD from the aspects of insulin resistance, autophagy, intestinal flora, genetic factors, extracellular vesicles, etc, so as to provide relevant references for the clinical treatment and research of NAFLD.