Objective To investigate the long-term clinical efficacy of large-channel posterior lumbar endoscopic open-window decompression (Endo-LOVE) in the treatment of single-segment lumbar spinal stenosis. Methods Prospective analysis 85 patients treated with large-channel Endo-LOVE by the same physician in the Department of Spine Surgery of The First Affiliated Hospital of Shihezi University from May 2018 to June 2021. The visual analogue rating scale for pain was used to assess the patients’ low back pain (VAS-LBP) and leg pain (VAS-LP). Numeric rating scale was used to assess the numbness of the lower limbs (NRS- LN), and modified ODI score to evaluate the patients’ living conditions; Minimum Clinically Important Difference (MCID) was used to assess whether the degree of improvement of the above indexes reached the clinical benefit. MacNab was used to evaluate the satisfaction rate of the surgical efficacy, and statistical information on the reoperation rate of the original segment at 3 years and perioperative complications was also obtained. Results Eventually, 53 patients completed the 3-year follow-up, with a follow-up rate of 62.35%. The patients’ operative time was 91.76±10.03 min, intraoperative bleeding was 16.68±7.92 mL, and the time to floor was 2.39±1.18 d. Compared with the preoperative period, the patients’ postoperative VAS-LBP scores at 1 year, postoperative 2 years, and postoperative 3 years, their VAS-LBP scores, VAS-LP scores, NRS-LN scores, and modified ODI scores reached clinically significant (MCID) (P< 0.05), with a MacNab excellence rate of 77.36% at the final follow-up. Conclusion The analysis of the three-year evaluation index of large-channel Endo-LOVE in this study showed that large-channel Endo-LOVE has superior long-term efficacy in the treatment of lumbar spinal stenosis and supports large-channel Endo-LOVE as one of the best surgical procedures for the treatment of lumbar spinal stenosis