Objective To assess the clinical application value of tranforaminal unilateral approach for bilateral decompression by comparing the short-term effectiveness of bilateral decompression via unilateral approach of intervertebral foramen with via small surgical incision of bilateral spinous process in lumbar interbody fusion for the treatment of lumbar spinal stenosis. Methods Between July 2014 and June 2015, 48 patients with lumbar spinal stenosis underwent decompression and internal fixation by unilateral approach in 24 cases (trial group) and by bilateral small incision approach in 24 cases (control group). There was no significant difference in gender, age, disease duration, disease type, involved segment, combined medical diseases, preoperative level of creatine phosphokinase (CPK), the visual analogue scale (VAS), and Oswestry disability index (ODI) between 2 groups (P>0.05). The operation time, intraoperative blood loss, postoperative drainage, hospitalization time, and the incidence of complications were recorded. The CPK levels were evaluated at 1, 3, and 7 days after operation. VAS score and ODI were used to evaluate the effectiveness, and lumbar X-ray film or CT scanning to determine the intervertebral bony fusion. Results There was no significant difference in operation time, intraoperative blood loss, and hospitalization time between 2 groups (P>0.05), but significant difference was found in postoperative drainage (t=5.547,P=0.000). At 1 day after operation, the level of CPK in the trial group was significantly lower than that in the control group (t=3.129,P=0.005), but there was no significant difference at 3 and 7 days after operation between 2 groups (P>0.05). The patients were followed up 12-24 months (mean, 17 months). All the wounds healed primarily. Heart failure occurred in 1 case of the trial group, and cerebrospinal fluid leakage and pulmonary infection, and nerve root injury occurred in 1 case of the control group respectively. There was no significant difference in the incidence of complications between 2 groups (χ2=0.273,P=0.602). The interbody fusion rate was 95.8% (23/24) in the trial group and was 91.7% (22/24) in the control group, showing no significant difference (χ2=0.356,P=0.551). No cage sink, dislocation or plate and screw loosening and breakage was found in 2 groups. No adjacent segment degeneration occurred during the follow-up, and there was no change of scoliosis and lumbar sagittal curvature. At 3, 6, and 12 months after operation, the VAS score and ODI were significantly improved when compared with the preoperative scores in 2 groups (P<0.05), and the VAS score and ODI of the trial group were significantly better than those of control group (P<0.05). Conclusion The bilateral decompression via unilateral approach of intervertebral foramen and small surgical incision of bilateral spinous process in lumbar interbody fusion have satisfactory efficacy for the treatment of lumbar spinal stenosis, but the tranforaminal unilateral approach has the advantages of less trauma, avoidance of bilateral muscle stripping and soft paraspinal muscle injury, retention of posterior spinal structure, faster postoperative recovery, shorter hospital stay and good short-term effectiveness.