Under conditions of hypoxia generalized vasoconstriction and remodeling of the pulmonary vascular leads to pulmonary vascular persistent resistance. The medial thickening is the main reason of pulmonary vascular remodeling and hypoxic pulmonary artery hypertension，pulmonary artery smooth muscle cells （PASMC） are the principal structure of media,and chronic hypoxia induces the imbalance of vasoactive substances and growth factors. Under this condition,the main medial thickening is believed to be attributable to proliferation,hypertrophy and increased accumulation of PASMC as well as expression of extracellular matrix proteins. Moreover,PASMC has an interaction with endothelial cell of intima and fibroblast of adventitia through multiple signal pathways and plays a crucial role in the development of pulmonary vascular remodeling. The article will make a summary of latest research on PASMC and mechanism of hypoxic pulmonary vascular remodeling.