Abstract: ObjectiveTo explore the inhibition of mouse interleukin-12 (IL-12) gene and THP on bladder cancer nude mice model. Methods After subcutaneous injection of EJ human bladder tumor cells to the nude mice subaxillary，Nude mice were divided into four groups randomly(Combine，IL-12，THP and control groups).Nude mice in Combine group were injected plasmid pCAGGS-mIL-12 on skeletal muscle and THP peritoneally.IL-12 group only were injected plasmid pCAGGS-mIL-12 on skeletal muscle；THP group were injected THP peritoneally；Control group were injected saline peritoneally and on skeletal muscle.All injections were carried two times per week for two weeks.The expression of IL-12 and IFN-γ in blood was assayed by an enzyme-linked immunosorbent assay (ELISA)at one week after injection.Mice were sacrificed at fourth week.The level of VEGF in tumor tissue was detected by immunohistochemistry.IL-12 and IFN-γ in tumor tissue was assayed by ELISA. Results In combine group，tumor growth were retarded compared with the other groups.There was a significantly low expression of VEGF in the combined group；IL-12 and IFN-γ were increased in both the IL-12 group and combined group. Conclusion Both injected pCAGGS-mIL-12 on skeletal muscle and THP peritoneally could inhibit the xenograft in nude mice planted with human bladder tumor cells.