The invention discloses a hepatitis B virus serum sample preserving diluent. The hepatitis B virus serum sample preserving diluent comprises Trise-HCL, NaCL, BSA, gentamicin sulfate, P-300, sunset yellow, lemon yellow and deionized purified water. On the basis of 1 L of the deionized purified water, the contents of Trise-HCL, NaCL, BSA, gentamicin sulfate, P-300, sunset yellow and lemon yellow are0.01 mol, 8.8 g, 20 g, 0.68 ml, 2.0 ml, 0.01 g, and 0.01 g, respectively. The hepatitis B virus serum sample preserving diluent of the invention has the advantages that the diluent comprises few components; the preparation method is simple; the prepared finished preserving diluent can protect the structure of a viral nucleic acid material from damage, inhibit the activity of DNase and effectivelyprotect the DNAs of a virus from degradation, has the advantages of stability, easy storage, convenience, etc., and is applicable to preservation and dilution of the hepatitis B virus (HBV DNA) serumsample. Test results prove that after addition of the preserving diluent prepared by the invention into the hepatitis B virus (HBV DNA) serum sample, DNAs and RNAs can be completely stored at 37 DEGC for 1 week, stored at 20-25 DEG C for 1 month, stored at 4 DEG C for 6 months and store at -20 DEG C or -80 DEG C for a long time.