Objective To study the main mechanism of pathogenic warm-dryness in causing diseases to mice.Methods The 216 Kunming species mice were randomized into normal temperature and humidity group

normal temperature and dryness group

and warm dryness group with 72 in each. The models were made under the simulated condition of warm-dryness. On the 7th day and 14th day

the observation on pathological changes of air passage and skin tissues

IgG-R of fluid of air passage

hemorrheology

bacteria attack experiment

and expression of bcl-2 and bax was carried out.Results Compared with the normal temperature and humidity group

in the warm dryness group the pathological changes of trachea

lung and skin tissues were obvious

the lung bacterial content increased

IgG-R decreased continuously

and plasma viscosity increased （P<0.01）

and expression of bcl-2 decreased.Conclusion The pathogenic warm-dryness damages the lung and consumes its body fluid

causing the IgG of fluid of air passage decreased and the resistance of "ciliary-mucus blanket" injured; the damaged body fluid gives rise to insufficient blood production

leading to the increased plasma viscosity; the failure of lung to disperse the body fluid induces the skin dried up

prepared the histological basis for the invasion of warm-dryness.