Abstract: ［Abstract］Objective　To investigate how to judge the vertebral canal is decompressed or not in the operation of thoracolumbar burst fracture via posterior approach．Methods　120 thoracolumbar burst fractures were treated with transpedicle screws-rods technique．We observed elaboratively if the posterior border of the burst vertebral body were pushed back into “one-line sign”or“antrorse arc line sign”on lateral fluoroscopy in the operation， and judged if the vertebral canal was decompressed．Comparing the data with CT scans after operation，there is a good concordance between the X-ray in operation and CT scan after operation with this method（P＞0.05）．Results　 The posterior border of the burst vertebral body and the dgree of compression of the vertebral canal could be oberved clearly on lateral fluoroscopy in the operation．There was a good concordance between the X-ray in operation and CT scan after operation with this method．Conclusion　The“straight line”or “antrorse arc line” can be observed clearly on the fluroscopy in operation．If the decompression for spinal canal be enough can be judged exactly with this method.