Objective:To observe the clinical efficacy of Modified Wuwei Xiaodu Decoction in the prevention and treatment of radiation pneumonia(RP)in patients with non-small cell lung cancer after chemotherapy. Methods120 patients with non-small cell lung cancer were randomly divided into the treatment group and control group,60 cases in each group. The control group was treated with conventional radiotherapy and chemotherapy,and the treatment group was treated with Modified Wuwei Xiaodu Decoction based on the treatment for the control group. The treatment course of radiotherapy and Chinese medicine were both one month. The incidence of RP and disease condition grades in both groups were observed,and the changes on Karnofsky performance status(KPS)score and serum transforming growth factor-β1(TGF-β1)that related to lung injury were compared.  Results:①A total of 110 cases completed the trial,among 55 cases in the treatment group and 55 cases in the control group(5 cases in each group fell off). The total expulsion rate was 8.3%. ②During the trial,the incidence rates of RP were 5.45% in the treatment group and 20.00% in the control group,the incidence rate of the treatment group was obviously lower than that of the control group(P<0.05). There was statistically significant difference on the disease condition grades between the two groups(P<0.05). ③After treatment,there was statistically significant difference on the KPS score between the two groups,and the score of the treatment group was obviously higher than that of the control group(P<0.05). ④After treatment,there was statistically significant difference on the TGF-β1 level between the two groups,and the level of the treatment group was obviously lower than that of the control group(P<0.05).  Conclusion:Modified Wuwei Xiaodu Decoction can be used in the prevention and treatment of radiation pneumonia in patients with non-small cell lung cancer after chemotherapy,which can obviously reduce the incidence of RP,ease the degree of acute radiation lung injury and improve the patient’s physical status.