Objective: To explore the curative effect of bilateral intermuscular approach and posterior median approach via transforaminal interbody fusion. Methods: A retrospective analysis of 62 patients with lumbar spine instability (L4/5) diagnosed in our hospital from May 2016 to May 2018 were retrospectively analyzed, using bilateral intermuscular approach and posterior median approach via intervertebral 31 cases of foraminal intervertebral fusion surgery. The follow-up time was 12 months. Record and compare the general preoperative data, perioperative data, follow-up data and imaging measurement results of the two groups of patients. Results: Operation time, intraoperative bleeding and postoperative drainage were significantly different between the two groups (P<0.05); there was no significant difference in the scores of VAS, JOA, ODI, etc. between the two groups before surgery (P>0.05), and the scores of the two groups were 3 months after the operation. The difference was significant (P<0.05), but there was no significant difference in the scores of the two groups at the last follow-up (P>0.05); there was no significant difference in the intervertebral space height and FCSA/TCSA value between the two groups before the operation (P>0.05). There was no significant difference in the height of the intervertebral space between the two groups at the last follow-up (P>0.05), but the FCSA/TCSA values were significantly different between the two groups (P<0.05). Conclusion: There is no significant difference in the long-term efficacy of the two surgical approaches. The bilateral intermuscular approach has short operation time, less bleeding, less drainage, convenient nail placement, and more functional units of the posterior median multifidus muscle. It is worthy of clinical application.