OBJECTIVE: To investigate the causes, clinical characteristics and diagnostic treatment of intervertebral space infection after posterior lumbar discoscopic disc removal and expandable intervertebral fusion. METHODS: In five cases of intervertebral space infection occurring after lumbar disc degenerative disease treated with discoscopy, local abscesses were removed by secondary open surgery, local antibiotics were placed for treatment, and the intervertebral fusion device B – twin was not removed. RESULTS: The patient was cured after 3 to 5 months with disappearance of infection symptoms, normal clinical test indexes and disappearance of abscess on imaging. Conclusion: The causes of intervertebral space infection after posterior lumbar disc fusion may include intraoperative contamination, low resistance of the patient, etc. The symptoms of lumbar and leg pain are mostly obvious, and can be cured by early second open surgery treatment.