Objective To study the effects of high-viscosity bone cement on bone mineral density and biomechanics after percutaneous kyphoplasty(PKP) for osteoporotic thoracolumbar fractures. Methods Clinical data of 95 patients with osteoporotic thoracolumbar fractures treated in our hospital from January 2015 to January 2018 were retrospectively analyzed, they were divided into observation group (50 cases) and control group (45 cases) by the Different filling bone cement, the control group was filled with low-viscosity bone cement, while the observation group was filled with high-viscosity bone cement. The visual analogue scale (VAS), bone mineral density, bone biomechanics index, Oswestry Dysfunction Index Questionnaire (ODI), intraoperative bone cement dosage and postoperative bone cement permeability were compared between the two groups. Results There was no significant difference in VAS score between the two groups in terms of intergroup and interaction(P＞0.05); after operation 12 months, the lumbar bone mineral density, the height of anterior vertebral margin and the midline height of the vertebral body in the observation group were significantly higher than those in the control group, and the Cobb angle and ODI scores were significantly lower than those in the control group[（0.87±0.07）vs（0.84±0.06），（13.60±1.45）vs（12.76±1.51）mm，（13.71±1.56）vs（12.95±1.63）mm，（11.08±1.50）vs（13.11±1.84）°，（28.02±2.36）vs（36.16±2.70）scores] (P＜0.05); there was no significant difference in the amount of bone cement between the two groups during operation(P＞0.05), the total bone cement permeability rate in the observation group was significantly lower than those in the control group during the follow-up period[6.00%vs20.00%] (P＜0.05). Conclusion The application of high-viscosity bone cement in PKP for patients with osteoporotic thoracolumbar fracture has a significant effect, whic can effectively improve the bone mineral density and bone biomechanical index, promote the recovery of vertebral function, and the leakage rate of bone cement is low and the safety is high.