The aim of this study was to evaluate the surgical safety and efficacy of the Posterolateral Interlaminar Approach (PIA) for treating Thoracic Disc Herniation (TDH). A total of 24 TDH cases were treated via PIA between January 2006 and August 2014. Japanese Orthopedic Association (JOA) scoring, Otani grading, and the Bridwell criteria were used to evaluate treatment efficacy. Twenty-four patients were followed up for between 6 months and 3.5 y, and were reviewed in the clinic at 3, 6, and 12 months after surgery. The preoperative JOA score was 4.4 ± 2.4 points, while postoperatively that at 3 months was 8.7 ± 2.3 points, and at the last follow-up was 9.0 ± 2.3 points. The comparisons over time were statistically significant (P<0.05). According to Otani grading, the treatment results of 9 cases were excellent, 11 cases were good, 2 cases were acceptable, and 2 cases were poor, with the excellent and good rate at 83.3%. All bone grafts achieved phase I healing within 9 months after surgery, and there were no occurrences of loosening of internal fixation, fracture, or segmental collapse during follow-up. PIA could obtain satisfactory clinical results in treating TDH.