n this study, we bred 17, 21, 25 lines of HBV transgenic mice by abreeding methodsim ilar to Sing le-founder Breeding. From the resultsof integration and repl icat ion detccted by Polymerase Chain Reaction(PCR)and Southern blotting, we learnt that HBV gene was transmitted steadilyfrom G0 to F5. Moreover, there was always HBV DNA of integrated inicein the serum. Serum HBV DNA was detectable in a high ratio, F1was 94% (102/103) , F2 F3 was 95.3% (61/64) , respectively. So, we canexactlyscreen transgenic mice from the offspring in the light of serumHBV DNA.