Objective To determine the predictive value of surgical Apgar score on delirium postoperatively following OPCABG. Method Intraoperative anesthesia data of patients underwent OPCABG during the period of January 2012 and December 2019 were reviewed and SAS score of each patient was calculated. Relationship between SAS score and postoperative occurrence of delirium were analyzed to determine the underlying mechanism. Results There are a total of 436 patients included with a mean age of 62.8±13.8 and 61.2±16.8 in each group. Patients in Delirium group had significantly higher incidence of heart failure (P=0.043) preoperatively in the Delirium group. No significant difference was observed referring to ASA PS III (P=0.102) and no significant difference was observed in duration of the surgery and anesthesia. Also no significant differences was observed as to dexmedetomidine and propofol use (P=0.256, P=0.278). The mean SAS score was in 4.2±0.8, 7.8±1.2 in two groups respectively (P＜0.001) and 96(22.02%) postoperative delirium events were recorded. Patients in Delirium group had much more EBL (P＜0.001) while LHR (P=102) showed no significant statistical difference between two groups. Univariate and multivariate regression analysis showed that the intraoperative SAS score was significant predictors of delirium following OPCABG (P＜0.001; P＜0.001). After adjustment for other clinical predictors, the addition of SAS also improved and the area under the curve to predict delirium was 0.934 (95%CI, 0.907-0.960, P＜0.001). Conclusions Intraoperative SAS score is associated with postoperatively following OPCABG and SAS score may be a valuable component to improve preoperative risk stratification of delirium among patient under OPCABG.