The robot-assisted radical cystectomy (RARC) is increasingly utilized. In patients undergoing RARC, Although prolonged Trendelenburg position and pneumoperitoneum can increase the cerebral blood flow, there were studies showed that the excessive cerebral perfusion can lead to encephalemia, which reduce the oxygen uptake of brain tissue and cause insufficient oxygenation of brain tissue at the cellular level. POCD may take place due to cerebral hemodynamic changes. Contemporary, intraoperative fluid restriction, a relatively long time of operation and surgical stress may also contribute to POCD.