Abstract: Objective To observe the effects of Rhodiola tibetica(R.tibetica)on lung tissue of rats with high altitude pulmonary edema and the expression of hypoxia-inducible factor-1a(HIF-1a)in the rats. Methods Totally 50 male SD rats were randomly divided into 5 groups:control group,normal saline treatment group,R.tibetica acclimatization group at low altitude(in Xi'an area with the altitude of 5 meters),hypoxia group,and R.tibetica acclimatization group at high altitude(in Naqu area with the altitude of 4500 meters).The changes of lung tissue of the rats were observed with light and electron microscope.HIF-1 expression in lung tissue was detected with immunohistochemical method and HIF-1a mRNA in lung tissue was determined with reverse transcriplase-PCR(RT-PCR). Results Observations of microstructure and ultrastructure of lung tissues revealed obvious high altitude edema in hypoxia groups and the mitigated edema in R.tibetica acclimatization group was observed.The expression of HIF-1a mRNA of R.tibetica acclimatization group at high altitude was significantly higher than that of control group and hypoxia group(0.463±0.069 vs 0.231±0.037 and 0.219±0.047,P<0.001). Conclusion R.tibetica can increase the expression of HIF-1a mRNA in lung tissue and mitigate high altitude pulmonary edema in hypoxic rats.