The diagnosis of hepatic encephalopathy is based on history, manifestations of neuropsychiatric abnormalities with ancillary tests such as blood ammonia measurements, and exclusion of other neuropsychiatric abnormalities and other disorders. 1. medical history, hepatic encephalopathy is usually present with a history of acute liver failure, cirrhosis, and/or extensive portal-body shunt. 2. manifestations of neuropsychiatric abnormalities. Neuropsychological testing reveals a range of abnormalities, primarily reflecting abnormalities in attention and processing speed functions. The main tests include traditional paper-and-pencil tests, such as the Psychological Hepatic Encephalopathy Score (PHES), the Repeatable Battery of Neuropsychological Status Tests (RBANS), the Inhibition Control Test (ICT), and the Critical Flicker Frequency (CFF) test. 3. Auxiliary tests. (1) Blood ammonia: the normal value of fasting venous blood ammonia enzyme method is 18～72mol/L. The arterial blood ammonia content is 0.5～2.0 times that of venous blood ammonia, and fasting arterial blood ammonia is relatively stable and reliable. Some studies have shown that arterial ammonia partial pressure can well reflect the severity of hepatic encephalopathy. (2) Neurophysiological tests: including electroencephalogram and brain evoked potentials. (3) Imaging tests: ① Cranial CT and MRI. ② Magnetic resonance mass spectrometry and functional MRI can obtain evidence of molecular and functional changes in the brain, and their efficacy in the diagnosis of hepatic encephalopathy is still in the research stage. In addition, abdominal CT or MRI is helpful in the diagnosis of cirrhosis and portal-body shunt. In addition, hepatic encephalopathy needs to be differentiated from other diseases that cause similar neuropsychiatric abnormalities, such as psychosis, craniosynostosis, toxic encephalopathy, and metabolic encephalopathy.