Objective:To study the effects of different carbon dioxide (CO 2) pneumoperitoneum pressures combined general anesthesia with sevoflurane-propofol on cerebral oxygenmetabolism balance and stress response in elderly patients undergoing colorectal cancer surgery. Methods:A retrospective collection of 100 colon cancer cases from February 2020 to February 2021 in the Jiading Branch of Shanghai First People′s Hospital (Jiangqiao Hospital, Jiading District) and the Shanghai First People′s Hospital were divided into low pressure group and high pressure group according to different CO 2 pneumoperitoneum pressure values, each with 50 cases and 12 mmHg(1 mmHg = 0.133 kPa) and 18 mmHg CO 2 pneumoperitoneum pressure values were used to inflate, and the perioperative status, cerebral oxygen metabolism status, and stress response of the two groups were observed. Results:The take food time, first time out of bed in the low pressure group were lower than those in the high pressure group: (45.67 ± 7.34) h vs. (49.67 ± 8.16) h, (34.69 ± 8.26) h vs. (39.87 ± 7.16) h, there were statistical differences( P<0.05). The time of first anal exhaust and hospital stay in the two groups had no significant differences ( P>0.05). Repeated measures analysis of variance results showed that the levels of partial pressure of carbon dioxide in artery, oxyhemoglobin saturation, arterial blood lactate acid, benous blood lactic acid were different followed the time and treatment methods ( P<0.05). The levels of heart rate, mean arterial pressure, cortisol and thyroid stimulating hormone in the low pressure group were higher than those in the high pressure group: (73.68 ± 6.35) beats/min vs. (84.84 ± 6.86) beats/min, (81.67 ± 13.68) mmHg vs. (93.68 ± 14.37) mmHg, (100.24 ± 12.34) μg/L vs. (135.68 ± 13.69) μg/L, (3.12 ± 0.43) mU/L vs. (3.54 ± 0.34) mU/L, there were statistical differences ( P<0.05). Conclusions:Different CO 2 pneumoperitoneal pressures affect the brain oxygen metabolism of patients, and clinical attention should be paid to them.