A loxP-EGFP-PolyA-loxP-Neo-loxP expression cassette was knocked into the Rag2 gene start codon site. As a Rag2 knockout mouse model, this stain can be used in subcutaneous inoculation of liver cancer tissues and tumor cells. Tumors can esaily form and grow. The amount of T and B lymphocytes in peripheral blood of mice was extremely low tested by FACS, which was comparable to or lower than that of Nude mice, and there was a significant difference compared with wild type mice. The pathological sections of HE staining of tumor tissues showed that the tumor sections of Rag2 KO mice and Nude mice were similar. This strain has the potential to replace Nude, NOD-SCID mice as a tumor-bearing mouse model.