Clinical symptoms of mild fatty liver are more insidious and often found in physical examination, while the symptoms of moderate to severe fatty liver are relatively obvious, and patients often seek medical attention with nausea, vomiting, jaundice and other symptoms, and the following tests can be performed to confirm the diagnosis when fatty liver is suspected: 1. 2-5 times of the upper limit, half of the patients can have 2-3 times higher alkaline phosphatase and γ-glutamyl transpeptidase, more than 80% of patients can have abnormal serum cholinesterase and serum bilirubin; 2, B ultrasound: B ultrasound is more sensitive to the detection of fatty liver, mainly based on the clarity of liver vessels, the degree of ultrasound attenuation and other graded diagnosis of fatty liver; 3, CT and magnetic resonance: CT is less sensitive than B ultrasound in the diagnosis of fatty liver. MRI is mainly used for those who have difficulty in diagnosis by ultrasound and CT examination, especially when focal fatty liver is difficult to be distinguished from liver tumor; 4. Histopathological examination of liver: it can perform clinicopathological typing of non-alcoholic fatty liver disease, and liver puncture under the guidance of B ultrasound is advocated to improve the accuracy of puncture and minimize liver damage.