Abstract: Objective To investigate the influence of edaravone on postoperative cognitive function in elderly patients undergoing knee replacement surgery. Methods Ninety ASA Ⅰ-Ⅱ elderly patients aged from 65 to 79 years old with MMSE score ≥ 23 who underwent knee arthroplasty surgery in our hospital from May to September in 2014 were randomly divided into edaravone group (group E, n=45) and control group (group C, n=45). Patients in group E were given edaravone accounting for 0.5 mg/kg while the same amount of sodium chloride injection in group C was given 30 min before anesthesia induction. The cognitive function of the patients was assessed preoperative, on the 1st and 5th postoperative day with the scale recommended by the international study of postoperative cognitive dysfunction. Results On the 1st postoperative day, the incidence of postoperative cognitive dysfunction were 11.11% and 33.33% in group E and group C; On the 5th postoperative day, the corresponding data was 6.67% and 22.22%, respectively. On the 1st and 5th postoperative day, the incidence of POCD in group E was lower than that of group C (P=0.01, P=0.04). Conclusion The data indicate that edaravone pretreatment can reduce the occurrence of POCD in elderly patients undergoing knee arthroplasty, improve the postoperative cognitive function of senile patients.