[Abstract] Objective: To study the effect of expandable interbody fusion cage in thoracolumbar spinal fusion for elderly patients with severe osteoporosis. Methods: 108 patients with severe osteoporotic thoracolumbar vertebral fracture were admitted to our hospital from March 2016 to December 2018. Fifty-two cases in the study group were treated with expandable interbody fusion cage, and 56 cases in the control group were treated with traditional cylindrical threaded fusion cage. Two groups of patients were compared in terms of general surgical indicators, wound pain scores before and after treatment, neurological function scores before and after treatment, and imaging indicators before and after treatment to evaluate the effect of different surgical methods. Results: (1) The operation time, intraoperative bleeding volume, postoperative drainage volume and hospitalization time of the study group were significantly lower than those of the control group, with significant difference between the two groups (P < 0.05). (2) Before treatment, the difference of VAS score between the two groups was not significant (P > 0.05); after treatment, the VAS score of the study group was significantly lower than that of the control group, the difference between the two groups was significant (P < 0.05). (3) Before treatment, there was no significant difference in ODI and JOA scores between the two groups (P > 0.05); after treatment, ODI and JOA scores in the study group were significantly lower than those in the control group, with significant difference between the two groups (P < 0.05). (4) Before treatment, there was no significant difference in Cobb angle between the two groups (P > 0.05); after treatment, the Cobb angle of the two groups was significantly lower than that before treatment, and the Cobb angle of the study group was significantly lower than that of the control group, with significant difference between the two groups (P < 0.05). Conclusion: Expansible intervertebral fusion cage has the advantages of safety, high efficiency and minimally invasive. It is conducive to avoiding surgical trauma, reducing subjective pain, promoting the recovery of spinal cord function and Imaging Anatomical reduction, and promoting the improvement of prognosis and quality of life of patients. Therefore, expandable intervertebral fusion cage is an ideal internal fixation method for elderly patients with severe osteoporotic thoracolumbar fusion.