Objective To summarize the clinical experience of laparoscopic pyeloplasty via transmesenteric approach, and explore the therapeutic effect of this procedure.Methods A retrospective analysis was made on the clinical data of 18 cases of children underwent laparoscopic pyeloplasty via transmesenteric approach from May 2014 to May 2020, including 10 males and 8 females, age from 3 to 14 years old, an average of (5.7 ± 2.9) years old. All patients are on the left. Through the transmesenteric approach, the incised mesenteric space is suspended on the abdominal wall with silk thread during the operation to facilitate the exposure of the surgical field. After cutting the excess renal pelvis, the Anderson-Hynes technique was used to perform ureteroplasty, and the ureteral stent was indwelling from the anastomotic site. Operation time, intraoperative blood loss, postoperative hospital stay, postoperative intestinal function recovery time, and summary of surgical skills and experience were recorded. After operation, color Doppler ultrasound and emission computed tomography (ECT) renal dynamic imaging were used to evaluate the effect of the operation.Results All the 18 cases were successfully completed without conversion to laparotomy. The operation time was 75 ~ 130 min, an average of (98.2 ± 17.7) min, the operative blood loss was 5 ~ 20 mL, an average of (10.0 ± 3.7) mL, the postoperative intestinal function recovery time was 1 ~ 4 d, an average of (1.9 ± 1.0) d. Postoperative hospital stay time was 2 ~ 5 d, an average of (2.1 ± 1.2) d. After 6 ~ 24 months of follow-up, the patient's clinical symptoms gradually disappeared. Ultrasound was re-examined 6 months after the operation: the anterior and posterior diameter of the renal pelvis was (7.9 ± 1.7) mm, which was significantly smaller than the preoperative (34.8 ± 2.0) mm (P = 0.000), the renal function of the operated side (40.1 ± 2.9)% was significantly improved (P = 0.000) compared with the preoperative (28.1 ± 3.0)% at 6 months after the operation, the success rate of surgery was 100%.Conclusion The transmesenteric approach laparoscopic pyeloplasty is safe and effective in the treatment of children with ureteropelvic junction obstruction (UPJO), and the trans-mesenteric space approach has little effect on the intestines of children, which is conducive to the rapid recovery of children after surgery.