Objective To evaluate the curative effect of cortical bone trajectory (CBT) screw in combination with pedicle screw in lumbar posterior decompression, bone graft and internal fixation for the treatment of osteoporosis lumbar degenerative diseases. Methods From February 2014 to April 2015, 32 patients with osteoporosis lumbar degenerative diseases underwent posterior decompression, bone graft and internal fixation after invalid conservative treatment. Internal fixation was performed by pedicle screws in 20 patients (A group) and by CBT screws combined with pedicle screws in 12 patients (B group). The recovery, operation time, intraoperative blood loss and VAS scores before and after operation, and JOA score were recorded in the two groups. Results The symptoms were improved in all the 32 patients. After surgery, JOA scores were significantly increased and VAS scores were significantly decreased. There were no significant differences in terms of operation time, blood loss, JOA score or VAS score between the two groups (P>0.05). In A group, one side pedicle screw placement failed due to osteoporosis in 2 cases and unilateral fixation was subsequently carried out. No poor screw holding force, nailing failure, or fracture breakage appeared in B group. No vascular or nerve damage caused by nailing was found in B group. The postoperative radiographic follow-up showed no screw loosening, fall-off or collapse; and the screw, connector, and fusion cage were all at the right position. There were no any adverse events in the two groups. Conclusion CBT screws in combination with pedicle screws in lumbar internal fixation have the advantage of less muscle and soft tissue injuries, strong screw holding force, and satisfied early curative effect in treating senile osteoporosis lumbar degenerative diseases.