Objective: To investigate the radiosensitized target of Fuzheng Zengxiao Formula (扶正增效方). Methods: The pulmonary adenocarcinoma (PAa) nude mice of tumor transplantation model were prepared and divided into four groups: Group I (blank control group, n=10), Group II (simple radiotherapy group, n=10), Group III (radiotherapy plus Fuzheng Zengxiao Formula, n=10) and Group IV (radiotherapy plus metronidazole, n=10). Radiation of Х-rays was given to the tumors in Group I, II and III when they were averagely about 1 centimetre in diameter. 23 hours later, the tumors were taken, the total proteins were extracted, and the protein contents were determined. The proteins were isolated with two dimensional gel electrophoresis, and the differentially expressed proteins were analyzed with mass spectrometry and identified by protein database. Results: Six significant proteins, including apolipoprotein E, ceratin75, S100A9, cyclophilin A, S100A10 and hemoglobin, were determined. Compared with Group I, apolipoprotein E and ceratin75 highly expressed in the Group II; compared with Group II, S100A9, cyclophilin A and hemoglobin had high expression in the Group III; compared with Group II, S100A9, cyclophilin A, S100A10 and hemoglobin had high expression in the Group IV; compared with Group IV, S100A9 and S100A10 had low expression and hemoglobin had high expression in Group III. Conclusion: The radiosensitization of Fuzheng Zengxiao Formula is related with the improvement of hypoxia state; and possibly S100A9 and cyclophilin A are the target proteins of Fuzheng Zengxiao Formula in radiosensitization. Objective: To investigate the radiosensitized target of Fuzheng Zengxiao Formula. Methods: The pulmonary adenocarcinoma (PAa) nude mice of tumor transplantation model were prepared and divided into four groups: Group I (blank control group, n = 10 ), Group II (radiotherapy plus Fuzheng Zengxiao Formula, n = 10) and Group IV (radiotherapy plus metronidazole, n = 10). Radiation of Х-rays was given to the tumors in Group I, II and III when they were averagely about 1 centimeter in diameter. 23 hours later, the tumors were taken, the total proteins were extracted, and the protein contents were determined. The proteins were isolated with two dimensional gel electrophoresis, and The differentially expressed proteins were analyzed with mass spectrometry and identified by protein database. Estimates: Six significant proteins, including apolipoprotein E, ceratin75, S100A9, cyclophilin A, S100A10 and hemoglobin, were determined. Estimators h Group I, apolipoprotein E and ceratin 75 highly expressed in the Group II; compared with Group II, S100A9, cyclophilin A and hemoglobin had high expression in the Group III; compared with Group II, S100A9, cyclophilin A, S100A10 and hemoglobin had high expression in the Group IV; compared with Group IV, S100A9 and S100A10 had low expression and hemoglobin had high expression in Group III. Conclusion: The radiosensitization of Fuzheng Zengxiao Formula is related with the improvement of hypoxia state; and possibly S100A9 and cyclophilin A are the target proteins of Fuzheng Zengxiao Formula in radiosensitization.