Objective This study aims to explore the application value and optimal interval of bispectral index (BIS) in sedation depth monitoring after selective posterior rhizotomy (SPR) in children with cerebral palsy. Methods Forty‑three children with cerebral palsy were enrolled in the Second Affiliated Hospital of Xinjiang Medical University from January 2016 to December 2016. The correlation between BIS and Ramsay score was analyzed by Spearman correlation. The receiver operating characteristic (ROC) curve was plotted to determine the optimal BIS interval for postoperative sedation monitoring. A total of 82 children with cerebral palsy were enrolled from February 2017 to April 2019. They were divided into an observation group and a control group according to the random number table method, 41 cases each. The BIS value was maintained at 55‒72 in the observation group after SPR sedation, and the Ramsay score was maintained at 2‒4 points in the control group. The sedation (insufficient sedation, satisfactory sedation, excessive sedation), incidence of adverse reactions (unplanned extubation rate, pneumonia, delirium) were compared between two groups. Results There was a significant negative correlation between BIS and Ramsay scores after SPR in children with cerebral palsy (r=−0.923, P<0.01). The optimal BIS range was 55‒72. The incidence of excessive sedation was 4.88% in the observation group, which was significantly lower than the 19.51% incidence of excessive sedation in the control group (P<0.05). There was no significant difference in the incidence of unplanned extubation, pneumonia, and delirium between the two groups (P>0.05). Conclusions The best BIS interval after SPR in children with cerebral palsy is 55‒72. Controlling BIS in this interval during postoperative sedation is beneficial to reduce the incidence of excessive sedation.