Objective To explore the incidence and related factors of postoperative cognitive dysfunction (POCD) of patients undergoing off-pump coronary artery bypass graft surgery (OPCABG). Methods Seventy two patients undergoing OPCABG in Renji Hospital Affiliated to Shanghai Jiao Tong University School of Medicine were enrolled. The POCD of patients was assessed by mini-mental state examination. Previous medical histories and perioperative information of patients were collected and related factors were analyzed.  Results The incidence of early POCD of patients undergoing OPCABG was 27.8%. Related influencing factors include history of diabetes (P=0.031), perioperative hyperglycemia (P=0.034), and history of cerebral infarction (P=0.044), which were all statistically significant. Conclusion The incidence of early POCD of patients undergoing OPCABG is high. Related influencing factors may include history of diabetes, perioperative hyperglycemia, and history of cerebral infarction, etc. Active preoperative intervention, maintenance of a proper blood glucose level, and good postoperative treatment are clinically significant for the prevention of POCD.