OBJECTIVE: To investigate the clinical characteristics and surgical treatment effect of ligamentum flavum ossificans type thoracic spinal stenosis (OLF-TSS). METHODS: From April 2004 to February 2010, 12 patients with OLF-TSS were treated with posterior enlarged total laminectomy + internal fixation. There were 7 males and 5 females; age 40-69 years old, average 53 years old; disease duration 40 days to 3 years, average 10.4 months. The average disease duration was 10.44 months. 1 case was combined with thoracic disc herniation. RESULTS: 7 patients received complete follow-up, with a follow-up period of 2-8 months (mean 4.71 months). Postoperative neurological decline was observed in 3 cases, and there was no significant difference in JOA scores between preoperative and two weeks postoperative, and there was a significant difference in JOA scores between preoperative and the last follow-up. 1 case suffered dural rupture during the operation, which was repaired and healed well. No other complications occurred. CONCLUSION: The etiology of primary OLF is unknown, and common symptoms include lower limb numbness and weakness, low back pain, intermittent claudication, fasciculation and sphincter dysfunction.MRI and CT examination are effective means to confirm the diagnosis. Posterior total laminectomy and decompression combined with internal fixation is a safe and effective method of treatment.