Abstract Purpose This study compares the efficacies of minimally invasive decompression by posterior microscopic mini-open technique combined with percutaneous pedicle fixation (hereafter MOT) to traditional open surgery in patients with severe traumatic spinal canal stenosis resulting from Arbeitsgemeinschaft für Osteosynthesefragen (AO) type A3 or A4 thoracolumbar burst fractures and provides references for clinical treatment. Methods In total, 133 patients with severe traumatic spinal canal stenosis caused by AO type A3 or A4 thoracolumbar burst fractures who underwent MOT (group A) or traditional open surgery (group B) were retrospectively enrolled. The demographic and radiological data of the two groups were analyzed and compared. Results A total of 64 patients were finally recruited in this study. There were no significant differences in gender, age, follow-up time, injury mechanism, injury level, AO classification, American Spinal Injury Association (ASIA) score, visual analogue scale (VAS) score, and duration of hospital stay between the two groups (P > 0.05). After the procedures, the prevertebral height ratio (PHR), the Cobb angle, and the mid-sagittal canal diameter compression ratio (MSDCR) were significantly improved (P 0.05). In contrast, a significant improvement in MSDCR was observed at the last follow-up when compared with the postoperative value (P < 0.05). However, the Cobb angle in group A was better maintained than in group B at the last follow-up (P < 0.05), while the MSDCR in group B demonstrated a greater improvement at the last follow-up than in group A (P < 0.05). Conclusions Both the MOT and traditional open surgery are effective treatment options for AO type A3 and A4 thoracolumbar burst fractures with severe traumatic spinal stenosis. The advantages of MOT include the minimally invasive procedure, extremely fine spinal canal decompression, less intraoperative bleeding, and significant pain relief. We suggest that MOT should be preferentially performed for AO type A3 or A4 thoracolumbar burst fractures with severe traumatic spinal stenosis.