Objective To discuss the effect of sevoflurane and propofol on cerebral oxygen saturation (rSO2) in patients with permissive hypercapnia through observing the real‑time changes of rSO2 in patients undergoing shoulder arthroscopic surgery and controlled hypotension. Methods A total of 52 patients who were scheduled for shoulder arthroscopic surgery, American Society of Anesthesiologists (ASA) grades Ⅰ‒Ⅱ, aged 18‒65 years, were enrolled. According to the random number table method, they were divided into two groups (n=26): a sevoflurane group (group S) and a propofol group (group P). All patients underwent the same induction protocol, before determination of the basic value of rSO2. During surgery, sevoflurane or propofol was used for anesthesia induction for group S and group P, respectively. After controlled hypotension, we adjusted ventilation strategy to gradually increase the partial pressure of end‑tidal carbon dioxide (PETCO2), and recorded the values of mean arterial pressure (MAP), heart rate, bispectral index (BIS) and rSO2 after PETCO2 reached 30‒35 mmHg (1 mmHg=0.133 kPa), 35‒40 mmHg, 40‒45 mmHg, 45‒50 mmHg and 50‒55 mmHg and stabilized for 5 min. The Mini‑Mental State Examination (MMSE) questionnaire was conducted one day before operation, and the first day and third day after operation. The score of questionnaire and incidence of postoperative nausea and vomiting were recorded. Results Compared with the basic value of rSO2, rSO2 in the two groups significantly decreased after controlled hypotension (P<0.05). Compared with the stage of 30‒35 mmHg of PETCO2, rSO2 in the stage of 35‒40 mmHg, 40‒45 mmHg, 45‒50 mmHg and 50‒55 mmHg of PETCO2 significantly increased (P<0.05). The rising trend of rSO2 along PETCO2 levels was more obvious in group S than that in group P. When PETCO2 was 50‒55 mmHg, rSO2 in group S was higher than that in group P (P<0.05). The difference of rSO2 between 50‒55 mmHg and 30‒35 mmHg in group S was higher than that in group P (P<0.05). Compared with MAP at baseline, MAP significantly decreased when PETCO2 was 30‒35 mmHg in the two groups. There was no significant difference in MAP, heart rate and BIS values between the two groups at various levels of PETCO2 (P<0.05). There was no significant difference in MMSE score and incidence of postoperative nausea and vomiting between the two groups (P<0.05). Conclusions When propofol or sevoflurane is used for anesthesia maintenance during shoulder arthroscopic surgery, permissive hypercapnia can effectively improve the decrease of rSO2 caused by controlled hypotension. However, compared with propofol, permissive hypercapnia can improve rSO2 more significantly during anesthesia maintenance with sevoflurane. The effect of these two anesthetics on postoperative cognitive function remains to be further studied.