Objective To find out the breeding rule of C 57 BL/6J-HBV transgenic mice and to establish a credible examination method of HBsAg. Methods Breeding characterization and expression of HBsAg of C 57 BL/6J-HBV transgenic mice in two different matings were compared. The nicety of serum diagnosis of HBsAg was conformed by immunohistochemistry, and the localization of expressed products in the liver cells was determined by laser scanning confocal microscopy.Results and Conclnsion The litter number of two different mating methods is nonsignficant( P >0.05),however the weaning number is significant(0.01< P <0.05).Positive rate of intercross mice is higher than that of backcross mice. Laser scanning confocal microscopy determines that HBsAg is expressed in the cell membrane and cytoplasm.