Hepatitis B virus, known as hepatitis B virus, is a member of the hepatophilic DNA virus and is the causative agent of hepatitis B patients. The hepatitis B virus can be transmitted through blood and blood products, close contact, especially sexual contact, vertical transmission from mother to child, and medical transmission. Hepatitis B vaccination is an effective means to interrupt the spread of hepatitis B virus. Newborns, close contacts of hepatitis B patients, medical workers and other high-risk groups should be vaccinated in a timely manner. Hepatitis B virus infection leads to various forms of liver damage or disease manifestations, including acute hepatitis, chronic hepatitis, asymptomatic carriers, various types of liver failure, cirrhosis and hepatocellular carcinoma. The severity and outcome of hepatitis B is influenced by many factors, such as the variability and replication level of the virus, the host’s immune function and the intensity and breadth of the nonspecific inflammatory response, as well as other comorbidities and other viral co-infections. Patients with hepatitis B virus infection should be promptly evaluated with hepatitis B virus DNA testing and liver ultrasound to assess the type of disease and guide treatment. In summary. The hepatitis B virus is the causative agent of hepatitis B patients and can cause hepatitis lesions through various routes of infection.