The reverse effect of hypoxic pulmonary hypertension (HPH) of Rhodiola algida Var.tangutica was researched.The hemodynamic changes were recorded and right ventricularhypertrophy index [RV/(LV+S)％] were calculated.The lung tissues were stained by HE andmorphological parameter of vascular wall thickness (WT％) was used to assess the remodelingof small pulmonary arteries.The mRNA and protein levels of endothelin 1 (ET-1) andendothelial nitric oxide synthase (eNOS) were measured by Real-time PCR and ELISAmethod.