Abstract: Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease worldwide with an increasing rate of morbidity year by year, affecting 25% of the global adult population. Its disease spectrum covers non-alcoholic fatty liver (NAFL), nonalcoholic steatohepatitis (NASH), NASH-related fibrosis, cirrhosis and hepatocellular carcinoma. Liver biopsy, as the "gold standard" for the diagnosis and staging of NAFLD, could not be widely used because of its limitations such as invasiveness, sampling variability and interobservers/intraobservers variability. With the increasing number of NASH patients, there is an urgent need for effective therapeutic agents, and a more urgent need to develop non-invasive markers to screen, diagnose and monitor patients, and evaluate the efficacy. This article reviews the research progress in non-invasive diagnosis of non-alcoholic fatty liver disease, including assessment of steatosis, diagnosis of NASH, and assessment of liver fibrosis.