Abstract:We introduced nu gene, from PBI/1 nude mouse, to 615/PBI beige mouse with NK cell deficient, and bred T and NK cell combined immunodeficient PBI/2 beige nude mouse. It is proved that this mouse is of T and NK , cell combined immunodeficiency.It has been successfully used in the experimental researches on tumor heterogenity,metastatic factors,genetic mechanism human tumor xenograft model which is difficult to establish in a single T cell deficient nude mouse and so on.