Objective To investigate the efficacy of biportal endoscopic transforaminal lumbar interbody fusion （BE-LIF） in the treatment of lumbar spondylolisthesis complicated with osteoporosis. Methods From June 2021 to June 2022， 36 cases of lumbar spondylolisthesis complicated with osteoporosis were treated with BE-LIF， including 9 males and 27 females， aged （65.94 ± 6.83） years （range： 51 ~ 76 years）. All were single segment， and the responsible segment was L_3/4 in 4 cases， L_4/5 in 26 cases， and L₅/S₁ in 6 cases. Imagingexamination showed 1 and 2 degree of spondylolisthesis in 28 and 8 cases， and degenerative and ischemic spondylolisthesis in 24 and 12 cases respectively. Preoperative average bone mineral density T value of the lumbar spine was （-3.19 ± 0.82） SD， and T value of the femur （-2.26 ± 0.86） SD. Oswestry disability index （ODI） was used to evaluate lumbar spine function； visual analogue scale （VAS） to evaluate low back pain and leg pain. ODI， VAS of low back and leg pain were recorded respectively before the operation， at discharge and at the last follow-up. MacNab criteria were used to evaluate the surgical efficacy at the last follow-up. The anterior and posterior disc height， segmental lordotic angle and percentage of slip were measured on the lateral lumbar X-ray films before and after the operation. All patients received standard anti-osteoporosis treatment after surgery. Results All patients completed the operation in one stage. The average operation time was （160.97 ± 35.01） min （range： 105~245 min）， and the average intraoperative blood loss was （72.50 ± 47.53） ml （range： 20 ~ 150 mL）. The mean follow-up time was （15.17 ± 6.53） months （range： 6 ~ 26 months）. There were statistically significant differences in both VAS score of back and leg and ODI score at discharge and last follow-up when compared with those before the surgery （F = 107.48， 103.66， 55.52， P < 0.001）. Macnab criteria of the last follow-up showed excellent in 21 cases， good in 12 cases， fair in 3 cases， and the excellent and good rate was 91.7%. Radiographic results showed that the height of the anterior and posterior disc height， segmental lordotic angle and percentage of slip were all improved immediately after surgery and at the last follow-up when compared with those before operation， but the anterior and posterior disc height， segmental lordotic angle at the last follow-up were decreased comparing with those immediate after the operation； the difference was statistically significant （P < 0.001）. The fusion rate at the last follow-up was 91.7% （33/36）. The complication rate was 13.8% （5/36）， including 1 case of intraoperative endplate injury， 1 case of nerve root cuff tear， 1 case of delayed postoperative wound infection， and 2 cases of posterior cage migration. Conclusion BE-LIF for the treatment of lumbar spondylolisthesis complicated with osteoporosis can achieve better immediate reduction effect， good clinical outcomes and high fusion rate in short-term follow-up， but the anterior and posterior disc height， segmental lordotic angle are partially lost at the last follow-up. There are still complications， and beginners should be cautious when performing the operation. Postoperative standardized anti-osteoporosis treatment is still an important measure to ensure the curative effect of surgery.