ObjectiveTo observe the lung injury of rats caused by PM2.5 induced imbalance of TH17/Treg immune system and the intervention effect of two different TCM treatments.Methods Wistar male rats were randomly divided into normal group, model group, TCM-treated group1 and TCM-treated group 2. PM2.5-induced lung injury model was established by airway instillation. Model group was given normal saline for gavage. TCM- treated group 1 and 2 were given Yupingfeng Powder and Guomin Decoction combined with Zhisou Powder for gavage. The pathological changes of bronchial and lung tissues, the contents of IL-8, IL-10, IL-17, NE, and MUC5AC in serum and BALF were compared, and the expressions of Foxp3 and IL-17 in lung tissue of each group were analyzed.Results Compared with normal group, the contents of IL-8, IL-17, NE and MUC5AC in serum and BALF of model group increased significantly, while IL-10 decreased significantly (P<0.05,P<0.01); the expression of IL-17 increased significantly and the expression of Foxp3 decreased significantly in lung tissue (P<0.01). Compared with model group, the contents of IL-8, IL-17, and NE decreased in TCM-treated group 1 and 2, while the content of BALF IL-10 increased significantly (P<0.05). The content of IL-10 in serum increased significantly in TCM-treated group 2 (P<0.05); the protein expression of IL-17 of lung issue decreased significantly, and the protein expression of Foxp3 increased significantly (P<0.01). The pathological changes were improved significantly.Conclusion PM2.5 can induce lung injury caused by the imbalance of TH17/Treg. Both two treatments can significantly improve the lung injury induced by PM2.5 and the imbalance of TH17/Tregs immune system.