Objective To investigate the relationship of peri-operative cerebral oxygen saturation (rSO2) with post-operative cognitive function in the elderly patients under edaravone injection combined with intravenous and inhalation anesthesia in order to establish the guides for clinical anesthesia practice. Methods Sixty ASA Ⅰ-Ⅱ elderly patients (＞60 years old) who were scheduled for selective abdominal surgeries or surgeries on lower limb in our hospital from January 2013 to January 2014 were enrolled in the study. The patients were randomly divided into 3 groups (n＝20), edaravone group 1 (E1: 100ml 0.9% NaCl containing 30mg edaravone), edaravone group 2 (E2: 100ml 0.9% NaCl containing 60mg edaravone), and control group (C, 100ml 0.9% NaCl). The above fluids were intravenously infused in 30 min during operation. All patients were not premeditated before anesthesia and given with atropine 0.5mg until entering the operation room. Anesthesia was induced with intravenous infusion of propofol, fentanyl and cisatracurium slowly. After tracheal intubation, all patients were mechanically ventilated to maintain partial pressure of CO2 at end-tidal (PetCO2) at normal range. rSO2 was continuously monitored and recorded during operation. Mini-mental state examination (MMSE), trail-making test, and grooved pegboard test were used to access cognitive function at 24h before and at 4, 8, 12 and 24h after surgery. Results (1) There was no significant difference in the general status among the 3 groups (P＞0.05). (2) No obvious difference was found in the scores of MMSE, trail-making test and grooved pegboard test among the 3 groups at 24h before operation (P＞0.05). (3) The patients of groups E2 and E1 had higher scores of cognitive tests than those of group C (P＜0.05), but there was no difference in the value of rSO2 among the 3 groups (P＞0.05). Conclusion Edaravone injection combined with intravenous and inhalational anesthesia reduces the incidence of postoperative cognitive dysfunction in the elderly patients, which may be related to its unique neuroprotective effect, elimination of free oxygen radicals, inhibition of lipid peroxidation, regulation of the relative apoptotic genes, and enhancement of tolerance to ischemia and hypoxia in central nervous system.