SummaryThis study aims to investigate the effects of obstructive sleep apnea on paediatric psychological and behavioural abnormalities. A total of 1086 paediatric patients with obstructive sleep apnea and 728 sample snoring controls were enrolled in the study. Patients with obstructive sleep apnea underwent bilateral tonsillectomy plus adenoidectomy or adenoidectomy alone. Repeated Autism Behaviour Checklist, Spence Children's Anxiety Scale, and Children's Depression Inventory were performed to assess the autism symptoms, anxiety level and depressive symptoms before and after surgery. The score of Autism Behaviour Checklist in preschool children with obstructive sleep apnea was higher than that in control. In school children with obstructive sleep apnea, the score of Spence Children's Anxiety Scale was also higher. School children with obstructive sleep apnea with depressive symptoms were significantly higher than that in control. The scores of Autism Behaviour Checklist, Spence Children's Anxiety Scale, and Children's Depression Inventory in the obstructive sleep apnea group after surgery were significantly lower than that before surgery. Our study showed that the score of Spence Children's Anxiety Scale and Children's Depression Inventory had a close correlation with the illness course and hypoxia duration. The Spence Children's Anxiety Scale and Children's Depression Inventory scores are also closely associated with the Autism Behaviour Checklist score. These results suggest that obstructive sleep apnea may have a significant impact on autism symptoms, anxiety levels and depressive symptoms in children. We found that the longer the duration of the obstructive sleep apnea course and hypoxia, the greater the impact on anxiety level and depressive symptoms. The suspected autism symptoms, anxiety level and depressive symptoms in children with obstructive sleep apnea were also significantly correlated. Thus, early detection and timely treatment may often reverse the psychological and behavioural abnormalities caused by obstructive sleep apnea.