Objective: To explore the role of interleukin 4(IL-4), expressions of cyclooxygenase-2 (COX-2) and platelet-derived growth factor(PDGF) in the model of chronic obstructive pulmonary disease(COPD), in the lungs of rats. Methods: Male Wistar rats were used to build up the model of COPD. Rats were randomly divided into the control group and model group, the IL-4 group and the dexamethasone group. The expressions of COX-2, PDGF-A and PDGF-B in the lung tissue were detected by western blotting and RT-PCR. Results: The expressions of COX-2, PDGF-A and PDGF-B in the model group were increased significantly. Those expressions in the IL-4 and dexamethasone group were notably decreased. Conclusion: IL-4 and dexamethasone could interfere in the establishment of COPD. The expressions of COX-2 and PDGF in the lung tissue of COPD were increased significantly and IL-4 and dexamethasone could decrease those expressions.