Abstract: Non-alcoholic fatty liver disease (NAFLD) is a chronic, non-communicable disease. In recent years, the prevalence and incidence of NAFLD have been increasing, while the age of onset has been decreasing. It has replaced chronic hepatitis B as the first chronic liver disease. This article reviews the research progress in the diagnosis of non-alcoholic steatohepatitis (NASH), and introduces the clinical history, pathological diagnosis and non-invasive diagnosis of NASH, in order to provide reference for clinical diagnosis of the disease.