[Objective] To measure the anatomical parameters of cortical bone trajectory (CBT) for lumbar percutaneous pedicle corti- cal placement in middle-aged and elderly persons, and explore the feasibility of CBT percutaneous screw placement. [Methods] The threedimensional CT data obtained from 50 middle-aged and elderly persons were imported into Aquarius iNtuition Viewer V4.4.6 software. The screw insertion angle, safety range, diameter and length of the nail path, the distance between skin screw insertion point and vertebral upper endplate and the distance between screw insertion point and spinous process axis were measured. [Results] There was no significant differ- ence in the distance from the skin entry point to the vertebral upper endplate (P＞0.05) , whereas there was significant difference in the dis- tance from the skin entry point to the spinous process axis from L₁ to L₅ (P＜0.05) . In transvers plane, the diameters of the nail path gradual- ly increased from L₁ to L₅, which was statistically significant (P＜0.05) . The actual length of the nail path in different segments was of statis- tical significance (P＜0.05) , which in the male proved significantly greater than that in the female segments (P＜0.05) . The ideal external de- viation angles of the nail path in each segment of lumbar spine remained consistent, with no significant differences (P＞0.05) . In sagittal plane, the diameters of the nail path gradually decreased from L₁ to L₅, which was statistically significant (P＜0.05) , while no significant dif- ferences in the diameters of the nail path were found between two genders (P＞0.05) . The ideal cephalad inclination angle remained un- changed from L1 to L5 (P＞0.05) , and was not significantly different between the two genders (P＞0.05) . [Conclusion] From the upper end- plate of vertebral body to the midline of spinous process, a body surface positioning point for CBT percutaneous pedicle screw might be as- sured, which varies among different segments. This point can provide reference for the CBT percutaneous pedicle screw placement in mid- dle-aged and elderly people.