Objective To investigate whether the sleep-induced hypoxemia ( SIH) at different time and different level have different effects on pulmonary emphysema and coagulation systemfunction in the rats with pulmonary emphysema. Methods Thirty Wistar rats were randomly divided into three groups( n = 10 in each group) . All rats were exposed to cigarette smoke twice a day ( 30 min each time) . From29th day on, the rats in Group A ( pulmonary emphysema with short SIH) were also exposed to mixed gas of 12. 5% oxygen for 1. 5 hours during sleeping time every day ( the expose time was divided into 4 periods, 22. 5 min each) . The rats in Group B ( pulmonary emphysema with mild SIH) were also exposed to mixed gas of 15% oxygen for three hours during sleeping time every day( the expose time was divided into 4 periods, 45 min each) . The rats in Group C( pulmonary emphysema with standard SIH) were also exposed to mixed gas of 12. 5% oxygen for three hours during sleeping time every day( the expose time was divided into 4 periods,45 min each) . After continuous exposure for 56 days, the rats were sacrificed. Semi-quantitative image analytic method was employed for histopathological analysis including pathological score of lungs, mean linear intercept ( MLI) and mean alveolus number( MAN) . ATⅢ, FIB, vWF, FⅧ were measured. Results All animals in three groups manifested the histopathological features of emphysema. Pathological scores of lungs and MLI of every group were significantly different from each other( F = 21. 907, F = 18. 415, all P lt; 0. 05) , Group A [ ( 61. 90 ±4. 25) % , ( 92. 45 ±1. 78) μm] and Group B[ ( 64. 60 ±3. 95) % , ( 92. 80 ±3. 65) μm] were significantly lower than Group C[ ( 73. 30 ±3. 86) % , ( 99. 32 ±2. 81) μm, q= 8. 96, q =6. 84, q = 12. 64, q =9. 65, all P lt; 0. 05] . Levels of FIB were significantly different among three groups ( F = 20. 592, P lt; 0. 05) while FIB in Group A[ ( 189. 98 ±5. 29) mg/ dL] and Group B[ ( 182. 70 ±2. 78) mg /dL] were significantly lower than that in Group C[ ( 198. 40 ±7. 37) mg/ dL, q = 4. 86, q= 9. 07, all P lt; 0. 05] , and FIB in Group A was significantly higher than that in Group B( q = 4. 20, P lt; 0. 05) . Levels of FⅧ were significantly different from each other( F = 33. 652, P lt;0. 05) while FⅧ in Group A[ ( 232. 26 ±4. 17) % ]and Group B[ ( 242. 53 ±14. 50) % ] were significantly lower than that in Group C[ ( 303. 25 ±32. 93) % ,q= 10. 73, q = 9. 18, all P lt; 0. 05] . Conclusions Pulmonary emphysema and hypercoagulable states increases with time and severity of SIH in rats with pulmonary emphysema. The elevated activity of blood coagulation factor may be a critical role in the hypercoagulable states.