Objective To explore the diagnosis of obstructive sleep apnea hypopnea syndrom(OSAHS) in children and to investigate the therapeutic effect of plasma low temperature tonsillectomy and adenoidectomy at low temperature on OSAHS.Methods One hundred and four pediatric patients were diagnosed as OSAHS by clinical manifestation,routine examination,fibrorhinopharyngescopy,X-ray at lateral rhinopharyngeal view and overnight polysomnography(PSG).Adenoidectomy and tonsillectomy was performed in 54 patients,only adenoidectomy in 28 cases and only tonsillectomy in 22 cases.Results Seventy four patients were cured,with 22 cases being improved evidently,6 cases being effective and 2 cases being ineffective.Conclusions Clinical symptoms and signs,X-ray at lateral rhinopharyngeal view,overnight PSG and so on were the major indexes for the diagnosis of OSAHS.Surgery was the best method for the treatment of OSAHS.