To investigate the applicability of 3DMIA1 software to upper airway modeling in children with obstructive sleep apnea hypopnea syndrome (OSAHS). A total of 30 children diagnosed with OSAHS by polysomnography were included in this study. Data regarding upper airway structure were collected via spiral CT while sleeping and awake, from which a threedimensional model of the upper respiratory tract from the nasopharynx to the supraglottic region using 3DMIA software was constructed. The upper airway olume and airway minimum cross-sectional area were measured employing software algorithms. Results: The upper airway volume and airway minimum cross-sectional area of the 30 children during sleep were significantly less than while awake (P <0.01). 3DMIA software modeling and software algorithm measurement were more objective than traditional radiology (e.g. Fujioka) with respect to evaluation of the extent of the upper airway narrowing in OSAHS