Hepatitis B DNA refers to hepatitis B genetic material. Viral genetic material can be divided into DNA and RNA, and hepatitis B virus belongs to DNA virus. The hepatitis B virus will replicate after invading the human body and replicate its own components. The DNA quantification of the hepatitis B virus can also be detected from the blood circulation, and this test is more commonly used in clinical practice, and regular monitoring can determine changes in the patient’s condition. If oral antiviral nucleoside analogues are taken, the DNA quantification of the hepatitis B virus will drop significantly when the drugs take effect. In clinical practice, this test is mainly used to test the effectiveness of nucleoside analogues and to monitor whether drug resistance has developed. The DNA quantification of hepatitis B virus is usually calculated in terms of IU/mL, or in some cases in terms of the number of copies/mL, up to 10^8, but clinically it is more common in the range of 10^3 or 10^4, and below.