Our aim was to study the changes in bone age and serum osteocalcin levels before and after adenotonsillectomy (AT) in children with obstructive sleep apnea hypopnea syndrome (OSAHS). A total of 58 OSAHS children (37 males and 21 females) with the mean age of 6.68 ± 1.11 years were enrolled and assessed by x-ray–based bone age estimation and enzyme-linked immunosorbent assay–based measurement of serum osteocalcin levels, before surgery and 6 months after AT. SPSS 19.0 software was used for statistical analysis. Our results revealed that bone age and serum osteocalcin levels in OSAHS patients were significantly lower than normal controls before AT (P < 0.05). Within 6 months after surgery, the bone age and the serum osteocalcin levels were significantly elevated in OSAHS patients (P < 0.05), compared with those before surgery. Serum osteocalcin levels and bone age are negatively correlated with apnea–hypopnea index, oxygen desaturation index, the percentage of the total recorded time spent below 90% oxygen saturation, and Epworth sleepiness scale scores (all P < 0.05). Our findings suggested that bone age and serum osteocalcin levels may be correlated with the development of OSAHS in children. AT may improve bone age and serum osteocalcin levels in OSAHS children.