The objective of study was to find the actions of astragaloside IV (ASIV) on PAH due to monocrotaline (MCT) in rats. Intraperitoneal injection of 60 mg/ kg MCT was injected to rats, come after by ASIV treatment with doses of 10 mg/kg daily once or 30 mg/kg of dose for twenty one days once daily. RVSP, serum inflammatory cytokines, RVH, and the other pathological parameters of the pulmonary arteries were evaluated. ASIV attenuated the increased pulmonary artery pressure and its structure in rat modification due to MCT. Additionally, ASIV avoided the rise in tumor necrosis factor (TNF)-α and interleukin (IL)-1β levels in the blood serum, and their expression of gene in the pleural parts, which was caused by MCT. ASIV promoted apoptotic resistance of HPASMCs and weakened the hypoxia-induced proliferation. ASIV shows over expression of caspase-3, caspase-9, p21, p27, and Bax, while ASIV downregulated Bcl-2, phospho-ERK, HIF-1α, and protein appearance in HPASMCs. These findings of the in vitro and the in vivo experiment indicate that astragaloside IV exerts protective effects against pulmonary arterial pressure, and may have action to be improved into pharmacological drug for pulmonary arterial pressure treatment.