Abstract: Objective: To establish the murine Lewis Lung Carcinoma cell tumor vaccine, LLC/IL- 12, which can stably express the IL- 12(interleukin-12) gene, and to assess the antitumor effect of 131I- 1E2 (anti-lung cancer monoclonal antibody 1E2 labeled with iodine- 131 ) through tail intravenous injection and the synergistic effect of IL-12vaccine on 131I- 1E2 target -ed therapy.Methods:LLC/IL-12tumor vaccine was prepared. Na 131I was used to label 1E2 Mab. The model of C57BL/6 mice-transplanted tumor was established and the distribution of 131I- 1E2 in mice in different groups was observed by tail in -travenous injection of 131I- 1E2 or combined with intratumoral injection LLC/ mIL- 12. When the tumors were large enough, 40 mice were divided into4 groups: (1) GT group (Gene therapy, i.e. LLC/mIL-12), (2) RIT group (Radio immunotherapy), ( 3) PBS group, and ( 4) GT+RIT group. Tumor volume and weight were measured and tumor-inhibitory ratio was calculated af-ter treatment. Analysis of CTL and NK activity was performed. Results: 131I- 1E2 could effectively target tumor tissue, espe -cially when combined with IL-12vaccine. RIT+GT can up-regulate the expression of IL-l2 gene and inhibit the tumor growth compared with GT or RIT alone. There was abundant CD4 + and CD8 + T lymphocyte infiltration in the GT and combined group, and NK and CTL cell activity was improved. There was more 131I- 1E2 accumulated in tumor tissue in the combination group. Conclusion: 131I- 1E2 can obviously inhibit tumor growth and has potential clinical application value.131I- 1E2 may possibly become a new tumor targeting agent.