Fatty liver is caused by the accumulation of liver fat in excess of 5-10% of the weight of the liver, resulting in fatty degeneration of the liver cells and damage to the liver cells. Fatty liver can be diagnosed from laboratory tests, physical examination, imaging tests, and liver biopsy. 1. Laboratory examination: after fatty liver patients progress to steatohepatitis, liver function will be abnormal, mainly manifested by the elevation of glutamic oxaloacetic aminotransferase, glutamic alanine aminotransferase, gamma-glutamyltransferase, and alkaline phosphatase. Due to the fact that most of the patients with fatty liver suffer from the combination of metabolic disorders, the laboratory tests such as lipids, cholesterol, triglyceride, academia, and uric acid also need to be looked at. 2. Physical examination: through abdominal palpation to know whether the volume of liver is abnormal, whether there is pain, and to observe whether the patient has yellow skin, yellow sclera, and other yellowing conditions. 3. Imaging examination: generally there are ultrasonography, CT, MRI, which are used to observe the degree of fatty liver and whether there are liver tumors. 4. Liver biopsy: Liver biopsy is to use a liver puncture needle to puncture the liver tissue and observe the liver tissue through a microscope, under the light microscope, more than 5%-10% of the liver cells are fat cells, accompanied by ballooning hepatocytes and inflammation in the liver lobules. If fatty liver is suspected, one should go to the hospital immediately and complete the relevant laboratory tests to confirm the diagnosis of fatty liver and the extent of the lesions.