OBJECTIVE： To observe the effects of remifentanil-induced controlled hypotension （CH） on postoperative cognitive dysfunction （POCD） and serum S100β protein in elderly patients underwent spinal surgery， and to investigate their relationship. METHODS： Sixty elderly patients undergoing selective laminectomy decompression internal fixation of lumbar or thoracic fractures under general anesthesia were selected prospectively from orthopedics department of our hospital during Jan. 2014-Dec. 2015， and then divided into CH group and non-CH group in accordance with random number table， with 30 cases in each group. Both groups received general anesthesia of injection and inhalation via endotracheal intubation. Mean arterial pressure （MAP） of CH group were reduced to 70％-80％ of the basic values by adjusting remifentanil infusion rate； those of non-CH group were maintained at basic level. Surgery duration， anesthesia duration， intraoperative blood loss， the incidence of POCD and serum concentration of S100β protein were observed in 2 groups. The relationship of serum concentration of S100β protein with POCD was analyzed， and the occurrence of ADR was recorded. RESULTS： The intraoperative blood loss of CH group was significantly less than that of non-CH group， with statistical significance （P＜0.05）. There was no statistical significance in the incidence of POCD between 2 groups on the 1st and 7th day after surgery （P＞0.05）. The incidence of POCD and serum concentration of S100β protein in CH group were significantly higher than in non-CH group on the 2nd and 3rd day after surgery， with statistical significance （P＜0.05）. The serum concentration of S100β protein may be related to the incidence of POCD （r＝0.992 7，P＝0.001 3）. CONCLUSIONS： Remifentanil CH used in elderly patients underwent spinal surgery can reduce intraoperative blood loss， but increase the serum concentration of S100β protein and the incidence of POCD at early stage.