Abstract: Objective To develop a rat model of particulate matter 2.5 microns (PM2.5) related chronic bronchitis,and study the effect of TCM Qing Fei Hua Zhuo Xing Xue Kuan Zhong prescription on lung histopathology and serum IL-8 and TNF-α levels in model rats. Methods Forty rats were randomly divided into control group,model group,low dose TCM group and high dose TCM group (10 rats in each group).The rats in the control group did not receive any treatment for 60 days;the rats in other three groups received post nasal drip of PM2.5 suspension(40 mg/kg once a day) for 60 days to develop an animal model.Then,the control group and model group received intragastric administration of 0.9% NaCl,the low-dose TCM group received intragastric administration of TCM Qing Fei Hua Zhuo Xing Xue Kuan Zhong prescription liquid medicine at a dose of 0.825 g/ml,and the high-dose TCM group received intragastric administration of TCM Qing Fei Hua Zhuo Xing Xue Kuan Zhong prescription liquid medicine at a dose of 1.65 g/ml,once a day for 15 days.After the treatment,the morphological changes of lung tissue were observed under light microscope,and the levels of serum IL-8 and TNF-α were tested. Results The levels of serum IL-8 and TNF-α in the model group were statistically different from those in the control group(P<0.05).After the treatment,the levels of serum IL-8 and TNF both in the low-dose and high-dose TCM group were decreased as compared with the model group (P<0.05).The pathologic findings showed that the pathological damage of lung tissue was repaired at different levels both in the low-dose and high-dose TCM group (P<0.05). Conclusion TCM Qing Fei Hua Zhuo Xing Xue Kuan Zhong prescription can repair the damaged lung tissue and improve the space of gas exchange in rats with chronic bronchitis caused by PM2.5,which may be related to the decrease of serum IL-8 and TNF-α.