Objective To observed the clinical efficacy of the bilateral interval pedicle screw placement for Lenke 1 adolescent idiopathic scoliosis(AIS).Methods Thirty-six patients (including 7 males and 29 females)with Lenke 1 AIS (mean age, 15.3years) were underwent posterior fusion using bilateral interval pedicle screw placement.The pro-operative coronal Cobb angle of main thoracic curve were less than 75°and the flexibility were greater than 50%.The following variables including pre-and post-operative sagittal and coronal Cobb angle, the distance between the C7 plumbline and the center sacral vertical line(CSVL),the distance from the C7 plumbline to the perpendicular line drawn from the superior posterior endplate of the S1 vertebral body(sagittal sacral vertical line[SSVL]), rib hump(RH), apical rib spread difference(ARSD), apical vertebral body-rib ratio (AVB-R) were observed to analyze the clinically outcome.Results The average operation time was 176 mins (150-240mins);the average blood loss was 840ml (range ,460-1100ml).All cases were successfully operated.No neurovascular injury was noted.1 case was complicated with left pleural effusion, 2 cases were complicated with superficial wound infection 2 weeks after operation.No serious complication related to surgery was presented.Coronal Cobb angle of major curve decreased significantly from 56.7°±7.98° of preoperative to 14.1°±6.04°of postoperative (P<0.05).There is no significant difference between the thoracic curve in postoperative X-ray and in the latest follow up X-ray pictures(Cobb angle 17.2±3.24°,P>0.05).Thoracic sagittal Cobb angle decreased significantly from 28.9°±7.89°of preoperative to 21.9°±10.6°of postoperative (P<0.05).There is no significant difference between the thoracic kyphosis in postoperative X-ray and in the latest follow up X-ray pictures(Cobb angle 24.3±5.08°,P>0.05).SSVL was changed from-11.7±12.1 mm to-1.39±9.38mm (P <0.05).There is no significant difference between the distance in postoperative X-ray and in the latest follow up X-ray pictures(-2.65±4.67 mm, P>0.05).RH were changed from 37.7±5.75 mm to 19.3±6.88 mm(P <0.05), ARSD was changed from 20.1±6.58mm to 8.11±4.70 mm (P<0.05) , AVB-R was changed from 1.56±0.16 to 1.22±0.20 (P<0.05).There were no differences in coronal plane balance between pre-, post-operation and the latest follow up.No failure of internal fixation was found during the follow up period.Conclusion Bilateral interval pedicle screw placement could gain good three-dimensional correction in treatment of mild to moderate Lenke 1 adolescent idiopathic scoliosis.