Objective To explore the mechanism of immune function in rats lung exposed to the extreme climate conditions. Methods Altogether six extreme climate conditions of sharp increase in temperature,sudden drop in temperature,continued high temperature,continued low temperature,high temperature with high humidity and normal temperature with high humidity,were obtained by using artificial climate simulation system. Melatonin (MT),interleukin-10 (IL-10),interleukin-6 (IL-6) and secretory IgA (sIgA) extracted from bronchoalveolar lavage fluid (BALF) and lung tissues were detected by enzyme - linked immunosorbent assay (ELISA). Results The content of MT and IL-10 from lung tissue decreased significantly in the process of sudden changes in temperature (P < 0.05),and there were significant differences in continued high temperature group and continued low temperature group (P < 0.05,P < 0.01). IL-6 and sIgA from BALF showed no significant differences in the process of sudden changes in temperature,while which changed significantly in continued high temperature group,continued low temperature group,high temperature with high humidity group and normal temperature with high humidity group (P < 0.05),furthermore,those in both high humidity groups were more than continued high temperature group and continued low temperature group. Conclusion The extreme climate conditions influence lung immune function differently by the way of corresponding response of different immune factors.