The B6-hFcRn (Extra) /hALB (HSA) mice were obtained by crossbreeding B6N-hFCRN (Extra) humanized mice with B6-hALB (HSA) humanized mice. In this model, the gene sequence encoding the extracellular domain of the FCRN protein in the mouse Fcgrt gene was replaced with the corresponding gene sequence from the human FCGRT gene, which is the binding site for the FCRN and IgG antibody Fc structure. Additionally, the mouse Alb gene sequence (including UTR regions) was replaced in situ with the human ALB gene sequence. Therefore, the B6-hFcRn (Extra) /hALB (HSA) mice can be used for in vivo studies of human IgG antibodies, drug development using human serum albumin (HSA) as a carrier, as well as for pharmacodynamic and pharmacokinetic studies.