To study the clinical features of obstructive sleep apnea (OSA) in children with obesity. A retrospective analysis was performed on the medical data of 33 obese children aged 7-15 years, who were diagnosed with OSA and received polysomnography (PSG) in the Department of Respiratory Medicine in Shenzhen Children's Hospital. Fifty OSA children with normal body weight, matched for sex and age, were enrolled as the control group. Among the 33 obese children with OSA, the three most common daytime symptoms were inattention in 30 children (91%), somnolence in 22 children (67%), and morning fatigue in 21 children (64%), and the three most common nocturnal symptoms were snoring in 27 children (82%), mouth breathing in 20 children (61%), and sweating in 16 children (49%). Compared with the reference values of normal children, both the OSA + obesity group and the control group had prolonged light sleep, shortened deep sleep, and a significantly shortened rapid eye movement (REM) period, while there was no significant difference in these indices between the two groups (P>0.05). The apnea-hypopnea index, obstructive apnea/hypopnea index, and oxygen desaturation index in both REM and non-REM periods in the OSA +obesity group were significantly higher than those in the control group (P<0.05), while the lowest blood oxygen saturation during sleep was significantly lower in the OSA + obesity group (P<0.05). The children with obesity and OSA have the main daytime symptoms of inattention, somnolence, and morning fatigue and the main nocturnal symptoms of snoring, mouth breathing, and sweating. There is no significant difference in sleep structure between OSA children with obesity and those with normal body weight; however, respiratory events and blood oxygen saturation decline are more severe in OSA children with obesity. Citation.