〔Abstract〕 To study the position of the projection point and the depth of the needle insertion point and depth on the standard or lateral lumbar spine when the lumbar cortical bone screw is implanted, and to provide a theoretical basis for correct nail placement. Ten L1-L5 spine specimens were used to dissect a single vertebral body. The insertion point of the cortical bone channel screw was the intersection of the vertical midline of the corresponding articular process on the corresponding vertebrae and the horizontal line of 1 cm below the ipsilateral transverse process. The open cone was open, the valgus angle was controlled at 10°, and the head tilt angle was 25°-30°. The guide needle was completely implanted into the cortical bone channel to determine the complete nail channel, and the inner sidewall of the pedicle was not damaged. Then the following data were measured and analyzed:(1) The clock recording position of the needle insertion point;(2) In the middle of the pedicle, the position of the needle tip: the projection point on the clock and the distance from the medial edge of the pedicle;(3) At the junction of the pedicle, the position of the tip of the guide pin, the distance from the medial edge of the pedicle;(4) At the position below the upper-end plate, the position of the clock of the guide pin records the position. The results showed:(1) The needle entry point was at 5 o'clock on the left side of the pedicle, and the right side was at 7 o'clock. The needle exit point was on the left side at 11 oʼclock, and the right side was at 1 oʼclock. In the middle part of the pedicle, the tip of the guide needle was close to the inner side of the pedicle in the middle and lower part of the pedicle projection.(3) At the junction of the vertebra and the pedicle, the guide needle was located at the upper pole of the pedicle.