OBJECTIVE: To investigate the safety, feasibility and effectiveness of Modified Umbilical Laparoendoscopic single-site Surgery (MU-LESS) in the treatment of varicocele. METHODS: The 48 cases were all male infertility patients admitted to the reproductive medicine center of our hospital. The age ranged from 20 to 42 years old, with an average of 26.5 years old. There were 28 cases on the left side alone, 3 cases on the right side alone, and 17 cases bilaterally. There were 13 cases of degree I, 26 cases of degree II, and 9 cases of degree III. The duration of the disease ranged from 15 months to 30 months. Preoperative color Doppler ultrasonography was performed in all patients, and the diameter of the internal spermatic vein was >2.0 mm, and the Valsalva test showed blood reflux. All 48 patients underwent semen analysis and all had weak spermatozoa. Lumbar and rigid anesthesia was applied in the supine position with head down and feet up at 15°. A 5-mm incision was made at the superior, left and right margins of the umbilicus, and a 5-mm Trocar was inserted with a 5-mm 30° or 0° laparoscope and instruments. The internal spermatic artery and vein were revealed and freed by cutting the retroperitoneum about 2-3 cm above the internal ring opening, preserving the internal spermatic artery and double ligating the internal spermatic vein with a silk thread, without disconnecting the vessel. If the lesion was bilateral, the opposite side was treated in the same way. The incision was closed with 5-0 absorbable sutures. Semen changes and the incidence of testicular atrophy and testicular sphingomyelia were observed on follow-up. SPSS 14.0 statistical software was used to analyze and compare the changes of semen parameters before and after surgery in 48 patients. RESULTS: All 48 surgeries in this group were successfully completed. The unilateral operation time ranged from 10 to 40 min, with an average of 18.5 min; the bilateral operation time ranged from 28 to 50 min, with an average of 35 min. The internal spermatic artery was successfully isolated and preserved in 40 cases, while the remaining 8 cases were collectively ligated due to bleeding during isolation, resulting in poor observation of the artery. The follow-up period was 6 months to 24 months. The semen was reexamined after surgery, and sperm motility improved in 40 cases (83.3%, 40/48), sperm motility returned to normal in 14 cases (29.2%, 14/48), testicular syringomyelia appeared after surgery in 5 cases (10.4%, 5/48), recurrence in 3 cases (6.25%, 3/48), and there were no cases of testicular atrophy. The umbilical incision healed well and was obscured by the surrounding folds, with inconspicuous scarring and good cosmetic results. Conclusion: MU-LESS high level ligation of the internal spermatic vein for varicocele is safe, effective and feasible, and has the advantages of less trauma and better cosmetic effect compared with the traditional LESS technique; preserves the internal spermatic artery, which is helpful for the improvement of sperm quality; reduces the application of special Port or homemade Port special instruments, and silk knotting reduces the application of Hemlock and Cost savings were achieved. However, due to the mutual interference of the operating rod instruments, it increases the difficulty of the procedure, lengthens the operation time, requires higher surgical skills and a longer learning curve, and requires a physician with some experience to complete.