To discuss the methods of diagnosis and treatment of obstructive sleep apnea hypopnea syndrome (OSAHS) in children. 285 patients diagnosed OSAHS by X-ray for lateral rhinopharyngeal view, fibrorhinopharyngescopy and overnight polysomnography ( PSG) were reviewed retrospectively the clinical symptoms and signs. The patients whose apnea hypopnea index(AHI) > or = 5/h, blood oxygen's saturation reducing over 0.03 are diagnosed as OSAHS. 255/285 cases were performed adenoidectomy and/or tonsillectomy and 9 cases were treated with continuous positive airway pressure (CPAP). The major symptoms of patients with OSAHS are snoring in sleep, breathing opening mouth, apnea, hearing loss. 281/285 cases were diagnosed as adenoid and (or) tonsil hypotrophy. Two hundred- fifty five cases received surgery, adenoidectomy and tonsillectomy in 205, only adenoidectomy in 47, simple tonsillectomy in 3. The clinical symptoms of 248 cases improved evidently after operations. Improved rate is 97.2%. In 1-3 months after surgery,PSG were checked in 105 patients again: AHI, the percentage of the sleep time for saturation monitored by pulse oximetry < 0.90, the longest time of apnea are improved than pre-operation. 9 cases using CPAP received good effects, 7 of 9 cases used CPAP were in pre- and /or post- surgery. Two cases were obesity hypopnea syndrome. Children with OSAHS has signification them-self; PSG is the major means for diagnosing. Surgery is main method for treating; CPAP can be as the method of treating for serious OSAHS in preoperative preparation and postoperative management.