〔Abstract〕 Objective To explore the effect of functional endoscopic sinus surgery (FESS) in the treatment of chronic rhinosinusitis in children. Methods A total of 50 children with chronic rhinosinusitis treated in Wuxi Children's Hospital from July 2018 to December 2021 were selected and divided into a control group and an observation group according to random sampling method, with 25 cases in each group. The control group was treated with conventional drugs, while the observation group was treated with FESS on the basis of the control group. The treatment effect, nasal mucosa function and complication rate were compared between the two groups. Results After treatment, the total effective rate, ciliary clearance rate and ciliary clearance speed of the observation group were higher than those of the control group, and the incidence of complications was lower than that of the control group, and the differences were statistically significant (P < 0.05). Conclusion FESS in the treatment of children with chronic rhinosinusitis can effectively improve their clinical symptoms and olfactory function, and the incidence of complications is low.