Objective:To observe the clinical efficacy of Yanghe Yifei decoction combined with Western medicine in the treatment of pulmonary fibrosis of the lung-kidney yang deficiency type. MethodsEighty patients with pulmonary fibrosis due to deficiency of lung and kidney yang were randomly assigned into treatment group and control group, 40 patients in each group. The control group was given oxygen, oral methylprednisolone and acetylcysteine, while the treatment group was given Yanghe Yifei decoction in addition. The two groups were treated for 3 months. The clinical efficacy was observed and the changes in symptom and sign score, HRCT score, lung function and serum levels of transforming growth factor-β1 (TGF-β1), interferon-γ (IFN-γ) and interleukin-17 (IL-17) were compared.  Results:①The total effective rate was 90.0% and 80.0% in the treatment group and the control group, respectively. The clinical efficacy was superior in the treatment group to that in the control group (P<0.05). ②There were significant differences in asthma, cough, expectoration, Velcro rale and HRCT scores in both groups before and after treatment (P<0.05); there were significant differences in asthma, cough and HRCT scores between the two groups after treatment (P<0.05). ③Vital capacity (VC) was improved in the treatment group after treatment (P<0.05); there was significant difference in the level of VC between the two groups after treatment (P<0.05). ④The serum level of IFN-γ increased and the serum levels of TGF-beta 1 and IL-17 decreased in both groups after treatment (P<0.05); after treatment, the serum level of IFN-γ was higher in the treatment group than in the control group (P<0.05).  Conclusion:Yanghe Yifei decoction combined with Western medicine shows satisfactory effect in treatment of pulmonary fibrosis of the lung-kidney yang deficiency type. It improves the clinical symptoms better than Western medicine alone and its mechanism of action may be related to up-regulation of the expression level of serum IFN-γ.