Fatty liver is caused by excessive accumulation of fat in the liver. The normal liver lipid content is about 5%, when the content of fat in the liver increases to 40% to 50%, or 1/3 of the whole liver lobules are fatty, fatty liver is formed when hepatocytes become steatosis. In the past, the detection of fatty liver mainly relied on autopsy and liver puncture tissue biopsy, which were difficult to carry out screening in the population due to their limitations. There are three general types of imaging tests for fatty liver: CT, magnetic resonance imaging (MRI), and ultrasound. CT can reliably diagnose fatty liver and is superior to B ultrasound and MRI in terms of accuracy of various diagnostic methods in imaging, and is a reliable imaging means to diagnose fatty liver, but the examination fee is high and there is the influence of radiation hazard, which is not easy to carry out routinely; MRI is too expensive and not easy for people to accept; while B ultrasound, because it is cheap, non-invasive and can examine the liver at multiple levels, can also clearly show the hepatobiliary system and detect biliary Ultrasound is the best means to diagnose fatty liver because it is cheap, non-invasive, and can clearly show the hepatobiliary system and detect biliary system diseases such as gallbladder stones, and provides convenience for fatty liver detection and is easy to be censored in a large area. However, the diagnosis of what causes fatty liver cannot be made. In terms of etiology, fatty liver is divided into alcoholic fatty liver and non-alcoholic fatty liver, which can be caused by one disease or by the simultaneous action or sequential involvement of multiple etiologies. There are many causes of fatty liver, and obesity, diabetes mellitus and chronic alcoholic liver disease are the three major causes of fatty liver. Therefore, adjusting the diet structure, insisting on the necessary exercise, maintaining relatively normal blood lipid and blood sugar levels, correcting bad habits, and supplementing with liver-protecting, lipid-removing and anti-fibrotic drugs when necessary, can prevent and treat fatty liver in an energy-efficient way.