[Objective] To compare the clinical efficacy of posterior endoscopic isthmic bone grafting combined with pedicle screw fixation and open isthmic bone grafting combined with pedicle screw fixation in the treatment of lumbar spondylolysis in young patients.[Methods] From June 2017 to January 2021, 22 patients with lumbar spondylolysis underwent surgical treatment, including 12 in the endoscopic group and 10 in the open group. The clinical and imaging results were compared.[Results] The intraoperative blood loss, ambulation time and hospitalization time in the endoscopic group were better than those in the open group (P<0.05), and there was no surgical site infection and postoperative drainage, but the operation time of the former was longer than that of the latter(P<0.05)). The VAS score and ODI of the two groups decreased significantly over time(P<0.05). The VAS score and ODI of the endoscopic group were better than those of the open group at 1 month and 3 months after operation(P<0.05). There was no significant difference between the two groups at the last follow-up(P> 0.05). In terms of imaging, the isthmus healing of the two groups increased significantly over time(P<0.05). After the last follow-up, all patients achieved isthmus bone healing. [Conclusion] The clinical efficacy of posterior endoscopic isthmic bone graft repair combined with pedicle screw fixation in the treatment of young lumbar spondylolysis is better than that of open isthmic bone graft repair combined with pedicle screw fixation.