Abstract： Objective To study the effect of Thromboxane A2 (TXA2) inhibitor on the proliferation of hypoxic pulmonary artery smooth muscle cells (PASMC) of porcines. Methods The methods of 3(4,5-dimethylthiazol-2-yl) -2,5-diphenyl tetrazolium bromide ( MTT), immunohistochemistry of Ki67 and TdTmediated dUTP nick end labeling(TUNEL) were employed to measure the proliferation, inhibition rate and apoptosis of PASMC. Results U46619, a thromboxane A2 agonist, could promote the proliferation and expression of Ki67 in PASMC under hypoxic and normal conditions. It could also inhibit the apoptosis of PASMC. Ozagrel, a thromboxane A2 inhibiter, inhibited the proliferation and the expression of Ki67 in PASMC under hypoxia. The inhibition rate was 71.4%, but it had no effect on the proliferation and expression of Ki67 in PASMC under normal conditions. It promoted the apoptosis of PASMC. Ozagrel could inhibit the action of U46619 in promoting the proliferation and expression of Ki67 in PASMC and inhibit the apoptosis of PASMC. Conclusion Ozagrel may be used in treating the pulmonary hypertension by inhibiting the proliferation of PASMC, pulmonary vascular remodeling, and promote the apoptosis of PASMC.