Objective To investigate the incidence of early postoperative cognitive dysfunction (POCD) in elderly patients after isoflurane anesthesia and to analysis the factors related to early POCD. Methods Sixty eight Joint replacement surgery patients aged 65 years and older were underwent inhalation anesthetic isoflurane. All patients finished a brief neuropsychological test before and after surgery. Patients were divided into the POCD group and normal group by the Z scores (at least two Z score of single case more than 1.96). The incidence of early POCD was calculated. Relevant factors were recorded and conducted correlation analysis. Results The incidence of early POCD under isoflurane inhalation anesthesia in elderly arthroplastic patients is 48.5%. There is no significant correlation between the occurrence of POCD and intraoperative hypotension and hypoxemia. Conclusion The incidence of early POCD under isoflurane inhalation anesthesia in elderly arthroplastic patients is 48.5%.