The compound containing nitro group(e. g. misonidazole and metronidazole or flagyl) is a electron-affinic sensitizer which now improve better radiosensitiveness of hypoxic cell in solid tumor. However, neurotoxicity has limited its clinical use. In order to enhance its radiosensitizing effectiveness and reduce its neurotoxicity, a bifunctional compound-metronidazole derivative(CM) had been synthesized which had a tumor-affinic property and radiosensitize hypoxic cells. A series of analyses (e. g. m. p determination, TLC, paper electrophoresis and UV, IR) proved this synthetic compound to be a metronidazole derivative(CM) . Its molecular formula is C,18,H,23,O,10, N,7,•1/2 H,2,O• Twelwe batches of this compound has been synthesized, and its purity was 98%, the synthetic method was stable. when labeled with ,99m,Tc, it produced ,99m,Tc-CM which could concentrate and maintain a high concentration in tumor in mice bearing S,180, within 24 hours after iv injection. The radioactivity ratio of ,99m,Tc retained in tumor with that of brain and muscle was 10~16 and 5~7 respectively, suggesting that ,99m,Tc-CM had a strong tumor-affinic property. Because of its lower concontration in the brain, its neurotoxicity was decreased. In LD,50, experimments, it indicated that its toxicity was lower than that of the original compound "flagyl" . when CM was chelated with Ca,++, to form CMCa and ip into S,180, bearing mice, after which the mice were locally irradiated with ,γ,-ray under tumor acute local hypoxic condition, then the results indicated that the growth inhibiting effect on S,180, in irradiated group with CMCa was strronger than irradiated (R) group alone. The tumor was inhibited by 77.4% within 10 days and higher than that of R group (p,<,0.05) . Its radiosensitizing enhancement ratio (SER) was 1.89 and its radiosensitizing effect was stronger than that of metronidazole. Therefore, CM had a obvioug radiosensitizing action.