Objective To explore the methods of breeding ,reproduction and genotype of GJB2 knock -out (cCx26KO) mice and further study the critical role of GJB2 mutation in the onset of nonsyndromic hearing loss (NSHL) .Methods Two pairs of transgenic mice (Cx26loxp/loxp and Pax2 -Cre/+ ) were inbreeded to produce Cx26loxp/-_Pax2-Cre/+ ones ,female of which were used to mate with the male Cx26loxp/loxp ones to finally get the Cx26loxp/loxp_Pax2 -Cre/+ mice(cCx26KO) .The genotype was done by PCR and Agarose gel electro-phoresis using genome DNA extracted from the mice tails .The c-ABR was used to detect the hearing ability of the cCx26KO mice .Results Both breeding and reproduction of cCx26KO mice were successful .It was fruitful to obtain four genotype mice(Cx26loxp/loxp_ Pax2-Cre / + ,Cx26loxp / -_Pax2-Cre / + ,Cx26loxp/loxp ,Cx26loxp /-) by the breeding Cx26loxp / -_Pax2Cre / + and Cx26loxp/loxp mice .The results of breeding were met with the Mendel's law .The c-ABR revealed elevated response threshold around 95 dB SPL in cCx26KO mouse compared to the wild type ones ,which further validated the accuracy of the PCR method .Conclusion The PCR method is cor-rectly identified sub pups genotype and the female Cx26loxp/-_Pax2-Cre/+ mice mating with the male Cx26loxp/loxp ones is an effective way to obtain the cCx 26KO mice .