To observe the hyperoxia stimulus to lung and intestinal mucosa of rats and the changes of the content of cytokines IL-1beta，IL-2，IL-6，TNF alpha，so as to explore the biological mechanisms of ‘Lung and Large Intestine being interior-exteriorly related’.Methods:The experiment set up two groups-normal group and the hyperoxia one-which the oxygen concentration was 40%.The content of IL-1beta，IL-2，IL-6，the TNF alpha of Bronchoalveolar lavage fluid and intestinal mucosa lavage fluid was compared.Results:After 5 days，compared with normal group，IL-1beta，IL-2 and IL-6 levels of both the Bronchoalveolar lavage fluid and intestinal mucosa lavage fluid dropped significantly (P<0.05)，and TNF alpha of both the Bronchoalveolar lavage fluid and Intestinal mucosa lavage fluid showed a trend of decline.Conclusion:Lung and Large Intestine have the synchronicity from the perspective of mucosal immunity，and it may be the important biological basis for lung and large intestine exterior-interior relationship.