Objective To evaluate the clinical efficacy and feasibility of using the expanding pedicle subtraction osteotomy (E-PSO) technique for the treatment of congenital severe thoracic angular kyphotic deformity.Methods We retrospectively reviewed a cohort of 13patients with congenital severe kyphosis admitted to our hospital from January 2010 to June 2015 including 5 males and 8 females,the average age is (34.9±20.5) years old (ranged 15-55 years old).The vertebral deformity in T7～83 cases,T8～93 cases,T9～102 cases,T10～114 cases,T9～111 case.All cases were treated by E-PSO technique.The multi-malformed vertebrae are considered as a complexus.And the osteotomy was performed within the complexus.The superior and inferior endplate of the complexus were reserved.After the osteotomy was completed,alternately pressed tightly closed the upper and lower parts.Results All cases were followed up for 10-42 months,with an average of 32 months.At the time of preoperation,postoperation andthe last follow-up,the deformity angle was 107.0°±3.5°,23.5°± 1.5° and 23.5°±0.2°;TK was 98.1°±7.6°,28.9°±3.0° and 29.5°±0.1 °,LL was 94.1 °± 1.5°,43.7°± 1.3° and 44.1 °±5.3°;SVA was (-0.6±39) mm,(1.6±7.9) mm and (6±0.7) mm,respectively;PI was 28.9°±1.6°,31.7±12.3°and 31.9°±2.1°;PT was 17.7°±1.9°,13.4°±3.4°and 13.1°±4.2°,SS was 11.3°±0.4°,18.2°±1.1° and 18.7°±2.1°,respectively.The sagittal parameters and spinopelvic parameters except SVA were significantly improved in the post-operation and the last follow-up compared with the pre-operation according to the image data.No significant loss of correction occurred during the follow-up,and there was no statistical difference.The preoperative VAS score was (5.7± 1.4) points,ODI score was (19.8±12.7) points.The last follow-up VAS score was (1.9±0.7) points,the ODI score was (9.2±0.7) points.No case of nerve damage,infection and other complications,and no dissection,displacement and rupture of internal fixation were found during the follow-up.Conclusion The use of E-PSO technique for the treatment of congenital severe thoracic kyphotic kyphosis is feasible and can achieve better curative effect.