In this study, we present in vivo and in vitro evidence showing that hypobaric upregulates the expression of STIM1 in rat distal intrapulmonary arteries which plays an important role in the hypoxia-induced PASMCs proliferation via SOC/Ca2+/NFAT pathway and may represent a novel therapeutic target for the prevention of hypoxia pulmonary hypertension. The gene discussed is STIM1; the disease is pulmonary hypertension.