Abstract: Objective:To compare the clinical outcomes of two kinds of operative strategy, i.e, emergency operation priority or treatment of hypoxemia (HO) first, in acute type A aortic dissection (TAAAD) patients with moderate to severe HO.Method:One hundred and fifty-two AAD patients in Stanford A type with moderate to severe HO, namely the oxygenation index (PaO₂/FiO2) ≤ 150, had not the complications which need emergency operation, such as acute ischemia in important organs caused by vascular dissection, severe aortic valve regurgitation and acute heart failure, or signs of aortic dissection rupture by CT scan.Among those patients, 62 patients received emergency operation (group NW), the other 90 cases were conservatively treated for HO first (group W).Preoperative, intra-operative and peri-operative clinical data of all the patients were collected.Result:The preoperative clinical data of the two groups had no significant difference, P>0.05.But in the W group, during the conservative treatment of HO, 82 patients required mechanical ventilation therapy;3 cases need to extracorporeal membrane oxygenation (ECMO);10 patients had renal insufficiency, 4 patients needed bedside hemodialysis therapy;8 cases died.The intro-operative data, including surgical procedure, time of cardiopulmonary bypass, aorta cross-clamping, deep hypothermic circulatory arrest, operation time, had no significant difference between the two groups, P>0.05.W group had lower rate of peri-operative mortality or morbidity, such as renal, respiratory failure, infection and the degree of HO, duration of mechanical ventilation, ECMO, bedside hemodialysis, ICU time and postoperative hospital stay, compared with NW group, P<0.05.And postoperative chest drainage and blood transfusion in NW group were significantly increased, P<0.05.But when overall consideration, the overall incidence of renal failure, bedside hemodialysis between the two groups had no obvious difference, P>0.05.The overall mortality, ECMO assisted circulation, mechanical ventilation time and ICU time of W group were betterthan those in NW group, P<0.05.Conclusion:For some AAD patients with moderate to severe HO, priority treatment of HO could reduce peri-operative mortality or morbidity and obtain better clinical outcomes.