Nucleoside (acid) class antiviral drugs for chronic hepatitis B is effective, convenient to take orally, only one a day, less side effects, but the medication time is long, usually need to use about 2 years or longer, after stopping the drug need to be regularly observed, long-term use are likely to occur virus resistance. 1, lamivudine (heptyn) the earliest nucleoside (acid) class of drugs used for anti-hepatitis B virus, marketed in China in 1999, is by far the most cumulative cases of oral anti-hepatitis B virus drugs. Lamivudine has a rapid onset of action, strong viral suppression, and is relatively inexpensive, but has a high rate of viral mutation and rebound after discontinuation of the drug. Treatment course: at least 2 years, midway mutation requires drug change; Caution: due to long-term use is prone to mutation resistance, the existing trend of withdrawing from the first-line drugs; 1-year clinical data: serum HBV-DNA conversion rate of 46%-70%, liver function in the ALT normalization rate of 41%-75%, e antigen seroconversion rate of 16%-21%. Drug resistance: 20% at 1 year, about 70% at 5 years. 2.Adefovir (Haverix, Daidin, Meizheng, Agmatine, Ugandine, Adesian) Adefovir was launched in China in 2005. Its main feature is low viral variation rate, no cross-resistance with lamivudine, and it is more suitable for patients with lamivudine variation or YMDD variation. However, adefovir has weaker antiviral ability, slower onset of action, and long-term use in individual patients can injure the kidney. Therapeutic course: at least 2 years, with a change of drug or combination of drugs required in the middle of the period of reduced efficacy; Caution: contraindicated in patients under 18 years of age; long-term use in individual patients can injure the kidneys; regular review of renal function after 1 year of use. Clinical data for 1 year of drug use: serum HBV-DNA conversion rate of 21%-51%, liver function in the ALT normalization rate of 48%-72%, e antigen seroconversion rate of about 12%. Drug resistance: 0% at 1 year, 5.9% at 3 years, 11% at 5 years. 3, entecavir (Boludin or Renzong) Entecavir (Boludin) was marketed in China in December 2005, and domestic entecavir (Renzong) was marketed in 2009. Entecavir has a fast onset of action, strong viral inhibition, and low viral mutation rate, but the chance of viral mutation increases in lamivudine-resistant patients, and is more expensive. It is suitable for patients with good economic conditions, high viral titers and severe disease who urgently need rapid viral suppression to alleviate the disease, and the treatment effect has been recognized by the majority of doctors. Treatment duration: at least 2 years; Caution: contraindicated in patients under 16 years of age, to be taken on an empty stomach. Clinical data of 1 year of medication: 70%-80% of serum HBV-DNA disappeared, 60%-78% of ALT normalization in liver function, about 18% of e antigen seroconversion rate; drug resistance: 0.4% of patients with initial nucleoside (acid) analogues for 2 years, 1.1% for 3 years, but 6% of patients with lamivudine resistance for 1 year, 14% for 2 years, 32% for 3 years. 4.Tebivudine (Sulbivir) was launched in China in April 2007, it is a moderately priced anti-hepatitis B virus drug with the dual advantages of potent, rapid viral suppression and high e antigen seroconversion rate. At the same time, tebivudine has a good safety profile and is approved by the US FDA as a pregnancy class B drug, while other nucleoside (acid) drugs are class C. Its antiviral rate is comparable to that of entecavir, with the only drawback being a moderate rate of drug resistance. Treatment depends mainly on the effect achieved at six months of administration, which can predict the effect of long-term use and drug resistance. Treatment duration: at least 2 years; Precautions: contraindicated in patients under 16 years of age; Clinical data at 1 year of dosing: serum HBV-DNA disappeared at a rate of 60-88%, liver function ALT normalized at a rate of 72-74%, and e antigen seroconversion rate of about 32%. Drug resistance: 5% of HBeAg-positive patients treated for 1 year, 21% for 2 years, 8.6% for HBeAg-negative patients for 2 years. 5.Tenofovir (tenofovir dipivoxil fumarate, TDF) is expected to be launched in China soon.