Abstract: To package recombinant lentivirus, recombinant lentiviral vector carrying CD gene and GFP reporter gene and using synthetic radiation-responsive promoter which contains eight CArG elements(E8) as their upstream regulation sequence was constructed and transfected into 293T cells with pHelper 1.0 vector and pHelper 2.0 vector. After EJ cells were infected by recombinant lentivirus and exposed to different doses of ¹²⁵I, the expression of GFP gene was observed and the ability to converting 5-FC to 5-FU was assayed. The recombinant lentiviral vector was established successfully and the titer of recombinant lentivirus was 2×10⁸ TU/mL. Exposure of lentivirusinfected EJ cells to ¹²⁵I, green fluorescence can be observed and 5-FU which was converted from 5-FC in cell supernatant can be detected. The green fluorescence was obviously observed at the dose of 55.5 kBq and 74.0 kBq, and the ultraviolet peak of 5-FU was the sharpest at the dose of 148 kBq. The results indicated that synthetic promoter can induce the expression of downstream CD gene and reporter gene after exposure of ¹²⁵I and provided a valuable contribution to the continued experiments on radionuclide ¹²⁵I therapy combination with CD gene/5-FC suicide gene therapy of tumor.