Objective To investigate the effectiveness of Y-shaped osteotomy for treatment of developmental coxa vara in children. Methods Between January 2008 and October 2011, 10 cases (14 hips) of developmental coxa vara were treated. There were 4 boys (5 hips) and 6 girls (9 hips), aged 5-12 years (mean, 7.8 years). All the children had obvious lameness and limitations of hip abduction, adduction, and rotation. The anteroposterior pelvic X-ray films showed that the collodiaphysial angle ranged from 46 to 110° (mean, 87°); Hilgenreiner-epiphyseal angle (HE) ranged from 36 to 93° (mean, 57°); and the articulotrochanteric distance (ATD) ranged from — 25 to 6 mm (mean, — 3 mm). The subtrochanteric Y-shaped osteotomy was performed and angle steel plate was used for internal fixation. Results All incisions healed by first intention without surgery-related complication. All cases were followed up 14-40 months (mean, 18 months). The symptom of lameness disappeared or obviously alleviated; the range of motion of hip abduction, adduction, and rotation were increased. Postoperative X-ray films showed that the vertical epiphyseal plate of proximal femur was returned to the horizontal. After operation, the collodiaphysial angle was 130-153° (mean, 137°); HE angle was 23-35° (mean, 27°); and the ATD was 3-22 mm (mean, 14 mm). According to LIU Jiande’s assessment standards, the results were excellent in 5 hips, good in 8 hips, and fair in 1 hip, and the excellent and good rate was 92.8%. The other children had no recurrence of coxa vara except 1 case after 30 months. Conclusion The Y-shaped osteotomy is a simple and effective method to treat developmental coxa vara in children, which can fully correct the deformity, and patients can exercise early because of firm internal fixation.