Objective:To analyze the distribution of TCM syndromes of obstructive sleep apnea hypopnea syndrome (OSAHS) in children and to explore the application value of polysomnography (PSG) in the diagnosis of OSAHS and differentiation of TCM syndromes. MethodsThe information of TCM syndromes and PSG data of 90 OSAHS children (case group) and 30 non-OSAHS children (control group) were collected to analyze the distribution of TCM syndromes, sex, age and disease severity of OSAHS children, and to compare the differences of PSG indexes between case group and control group as well as among cases with different TCM syndromes.  Results:①Among 90 OSAHS cases, the top 10 symptoms or signs ranked by occurrence frequency were snoring, adenoid enlargement, mouth breathing, apnea or awakening due to suffocation, tonsil enlargement, daytime drowsiness, susceptibility to common cold, tiredness, hyperhidrosis and poor appetite. ②The most common TCM syndromes of OSAHS children were phlegm-dampness interaction syndrome (42.2%), followed by lung-spleen qi deficiency syndrome (31.1%) and lung meridian stagnation-heat syndrome (26.7%); Male OSAHS cases were more than female ones (P＜0.05). The number of OSAHS children aged 3-6 was more than that of OSAHS children aged 7-12 (P＜0.05). ③Compared with the control group, the obstructive apnea index (OAI) and apnea hypopnea index (AHI) increased in OSAHS children with lung meridian stagnation-heat syndrome, phlegm-dampness interaction syndrome and lung-spleen qi deficiency syndrome (P＜0.05), while average oxygen saturation (SM) and minimum oxygen saturation (SN) decreased (P＜0.05). Compared with the cases with lung meridian-heatstagnation syndrome and spleen-lung qi deficiency syndrome, OAI and AHI increased in OSAHS children with phlegm-dampness interaction syndrome (P＜0.05) while SM and SN decreased (P＜0.05).  Conclusion:The most common TCM syndrome of OSAHS children is phlegm-dampness interaction syndrome. PSG is beneficial to the objectification and standardization of TCM syndrome differentiation in children with OSAHS.