Background: Previous retrospective study suggested that acute lung injury (ALI) is frequent (78.49%) in patients undergoing aortic dissection surgery, and accompanied by a number of untoward consequences, and even induces death. Methods: This prospective single-center cross-sectional study, registered in the ClinicalTrials.gov (Identifier: NCT01894334), assessed the preoperative clinical variables and serological results from 130 adult patients scheduled for Stanford type-A acute aortic dissection (AAD) surgery at Beijing Anzhen Hospital between January 2013 and July 2014. Exclusion criteria included patients with coronary heart disease, severe heart failure, severe cardiac tamponade and severe nervous system abnormalities. Preoperative ALI was identified according to oxygenation index (OI) calculated by PaO2/FiO(2) ratio after anesthesia induction, and all the patients were divided into two groups: non-ALI (OI >= 300 mmHg) and ALI (OI <300 mmHg). The primary endpoint was the incidence of preoperative ALL. The secondary endpoints were the independent factors affecting the occurrence of preoperative ALL. Results: The incidence of preoperative ALI was 53.8%. With adjusted multiple logistic regression analysis, age [odds ratio (OR) 1.14, confidence interval (CI), 1.06-1.22; P=0.0002], body mass index (BMI) (OR 1.31, CI, 1.09-1.56; P=0.0033), preoperative diastolic blood pressure (DBP) (OR 0.94, CI, 0.89-0.99; P=0.0109), interleukin-6 (IL-6) (OR 1.03, 95% CI, 1.01-1.06; P=0.0053), and prostaglandin I-2/thromboxane B-2 (PGI(2)/TXB2) ratio (OR 0.25, 95% CI, 0.09-0.67; P=0.0055) were significantly related to the occurrence of preoperathe ALI. The decreased risk of ALI was related to the preopera the DBP value up to 44 mmHg (OR 0.935, 95% CI, 0.895-0.978; P=0.0033). Interactions analysis revealed that serum lactic acid mediated the relationship between DBP and ALI before Stanford type-A AAD surgery. Conclusions: In adults undergoing Stanford type-A AAD surgery, the incidence of preoperative ALI was 53.8%, and age, BMI, preoperative DBP, IL-6, and PGI2/TXB2 ratio w ere independent factors rel ated to the occurrence of pre-operative ALI. Trial Registration: ClinicalTrials.gov, Identifier: NCT01894334.