Objective：To investigate the effect of microscopic unilateral laminotomy for bilateral decompression (ULBD) with “over-the-top” technique by minimally invasive approach in treatment of single-level central lumbar spinal stenosis. Materials and Methods：This study included 30 patients with central lumbar spinal stenosis underwent microscopic unilateral over-the-top bilateral decompression by minimally invasive approach. The operation time, intraoperative blood loss, postoperative hospital stay, complications were recorded. The imaging were observed before and after the operation. The lumbar visual analogue scale (VAS) scores, Oswestry disability index (ODI) and the MacNab functional score were used to evaluate the patients'' low back pain and functional improvement. Results：There were no complication such as wound infection and splitting occurring in the patients after the surgery. The operation time was within 60-140 min, the intraoperative blood loss was within 50-300 ml, and the post-operative time of early ambulation was within 6-24 h. Patients were followed up for 3 to 24 months. Postoperative reconstruction of CT showed that the anteroposterior diameter of the spinal canal and bilateral lateral recess were improved than those before surgery (P< 0.05). The clinical symptoms of all patients released or disappeared after surgery. The VAS scores of the patients with low back pain were significantly improved at 3 days after the operation and at the last follow-up. The difference was statistically significant (P< 0.05). At the last follow-up, the clinical efficacy was evaluated using the MacNab scores: excellent in 21 cases, good in 8 cases, and fair in 7 cases, with an excellent and good rate of 96.7%. Conclusions：Microscopic unilateral laminotomy for bilateral decompression with “over-the-top” technique by minimally invasive approach is a safe and effective treatment for the elderly with lumbar single-level central spinal stenosis. This surgery does not destroy muscles with less tissue interference and preserves spinal stability. The mid-term effect is good, and the long-term efficacy needs further follow-up observation.