Objective To determine the risk factors associated with preoperative hypoxemia in acute type A aortic dissection. Methods The clinical data of 70 patients undergoing surgery for acute type A aortic dissection were collected from January 2013 to May 2014. Preoperative hypoxemia was defined by an arterial partial oxygen/inspired oxygen fraction (PaO₂/FiO₂) ratio ≤200 under static oxygen inhalation, and the patients were divided into hypoxemia group (n=21) and non-hypoxemia group (n=49) accordingly. The following data were collected, including age, gender, body mass index, smoking, drinking, history of hypertension, diabetes mellitus, coronary disease, CRP, D-dimer, PT, creatinine, BNP, ESR, IL-6, LVEF, pericardial effusion, the dissection involving renal artery, and mesenteric artery. The relationship between preoperative hypoxemia and the above data were analyzed by differences test and logistic regression analysis. Results We found that the body mass index, CRP, D-dimer, IL-6 and the dissection degree and involvement(renal artery and mesenteric artery) were significantly different between the hypoxemia group and non-hypoxemia group (P<0.05). According to logistic regression analysis, the independent predict factors for preoperative hypoxemia included CRP and D-dimer. Conclusion Body mass index, systemic inflammatory response, blood D-dimer, and dissection degree and scope are associated with preoperative hypoxemia. And CRP and D-dimer are the independent risk factors for preoperative hypoxemia in patients with acute type A aortic dissection.