【Abstract】 Objective To identify the effect of Erythropoietin (Epo) in prevention of Postoperative cognitive dysfunction (POCD) early and late after cardiac surgeries. Methods In this clinical randomized doubleblind controlled trial, 120 patients Patients were randomly divided into control group (group C, n=60) and Epo group (group E, n=60). Patients in group E received Epo 500 U kg-1 for three consecutive days before surgery, while patients in group C received normal saline. The montreal cognitive assessment (MoCA) were used to measure patients′ cognitive function the day before injected Epo or normal saline (T0), three to five days after(T1), 3 months (T2) and 6 months(T3) after surgery for both groups。 The time to extubation, days of mechanical ventilation,length of ICU and hospital stay were observed.Results As compared to Group C, MoCA scores showed significant improvement at T1 and T2 in group E (P＜0.05), while there was no significant difference in at time T3(P＞0.05). Compared to Group C, the extubation time and mechanical ventilation time of patients were significantly decreased in group E (P＜0.05). There was no significant difference in length of ICU and hospital stay(P＞0.05). Conclusion Preoperative administration of Epo protects patients from shortterm POCD following cardiac surgeries.