Objective To compare the clinical efficacy of oblique lumbar interbody fusion (OLIF) and posterior lumbar interbody fusion (PLIF) in patients with lumbar spinal stenosis (LSS). Methods 50 patients with LSS treated in the People's Hospital of Shanxi Medical Unviersity from June 2017 to June 2019 were studied retrospectively. 22 cases of OLIF and 28 cases of PLIF were performed in the spine diseased area. Among them, there were 10 males and 12 females in the OLIF group, aged (62.1±10.2) years old,14 man and 14 woman in the PLIF, aged (60.5±12.2) years old. The hospital stays, time for ambulation, hemoglobin (Hb) decline, the extent of surgical incision, surgery time, and blood drop during surgery, preoperative and postoperative visual analogue scale (VAS), Oswestry disability index (ODI), anteroposterior diameter (APD) and crosssectional area (CSA) of spinal canal, the width of the intervertebral foramen, the height of the intervertebral space and the intervertebral foramen were compared between the OLIF and the PLIF group. Results The hospital stays, time for ambulation, hemoglobin (Hb) decline, the extent of incision, surgery time, and blood loss during surgery in the OLIF group were less than those in the PLIF group (P＜0.05). The score of VAS in the OLIF group was less than PLIF after a month which was statistically significant (P＜0.05). One year later, PDH in the OLIF group was better than the PLIF group which was statistically significant (P＜0.05), there were no statistically significant differences in the other imaging indicators between two groups (P＞0.05). In terms of postoperative complications, in the OLIF group, there was 1 case of psoas major injury, 1 case of postoperative cage subsidence, and 1 case of numbness and pain in the left lower limb, in the PLIF group 2 cases of transient leg pain,1 case of infection, and 2 cases of incision redness with blisters and 1 case of cerebrospinal fluid leakage.Conclusion The efficacy of OLIF in LSS patients is comparable to that of PLIF, with higher recovery of posterior margin height of intervertebral space, faster recovery, less bleeding and less trauma, but it cannot completely replace PLIF.