Abstract: ［Abstract］Objective To explore the role of prostaglandin E2 （PGE2） in the pathogenesis of chronic obstructive pulmonary disease（COPD）and lung cancer. Methods　Sixty rats were randomly divided into A， B and C groups， 20 in each group. Rats in group A were given intratracheal injection of 3，4-benzopyrene-coin oil mixture to induce lung cancer model. 20-week later all rats were given CT scans of the lungs，then the lung lesion were observed and performed by pathological examination. Rats in group B were given passive smoking and injection of lipopolysaccharide to induce the COPD model，lung pathological examination was given on 29day to observe the COPD pathology. Rats in group C received no treatment and as control. PGE2 Elisa Kit was used to test the serum levels of PGE2 of rats in group A，B，and C. The data were analyzed by using statistical software SPSS 17.0. P＜0.05 was regarded as a statistically significant difference. Results The serum levels of PGE2 in lung cancer group and COPD model group were significantly higher than those in control group，P＜0.05， the difference was significant. Conclusion Our research confirms the high serum levels of PGE2 in lung cancer and COPD， suggesting that COPD and lung cancer may have common pathogenesis.