We proposed a concept model for the pathogenesis of obstructive sleep apnea syndrome (OSAS) in children. This concept model consists of three circles: adenotonsillar hypertrophy, obese and complex high risk. Each patient's severity and treatment efficacy depend on the combination area to which the patient belongs in this concept model. Overnight polysomnography (PSG) is recognized as the gold standard, but is not easy to perform in every institution for all OSAS-suspected children. PSG is recommended especially for children with problem behaviors suggestive of attention-deficit/hyperactivity disorder, mild-moderate OSAS for determining surgical indications, postoperative snoring children, and children with high-risk complications for the detection of central apnea hypopnea or central hypoventilation syndrome.