Objective: To evaluate the efficacy and safety of Institution Urology of Peking University modified technique for transperitoneal laparoscopic pyeloplasty combined with deflectable tip rigid ureteroscope(the Sun's ureteroscope) in ureteropelvic junction obstruction(UPJO) complicated with renal calculi. Methods: From January 2018 to September 2018, eight patients, including five males and three females, were diagnosed as UPJO with coexistent ipsilateral renal calculi in Peking University First Hospital and Changzheng Hospital of Second Military Medical University. The age ranged from 14 to 50 years(mean 28 years). Four patients had flank pain and one patient had flank pain with hematuria, while the other three patients came without clinical symptom.The BMI ranged from 16.8 to 26.2 kg/m²(mean 22.0 kg/m²). The lesion located on the left side in 4 cases and on the right side in 4 cases. One patient suffered with multiple pelvis stones. Four patients suffered with multiple lower calyceal stones, and 3 patients had solitary lower calyceal stone. The stone size ranged from 2 mm to 10 mm (mean 6.4 mm). 3 cases had slight hydronephrosis and 5 cases had moderate hydronephrosis. Two patients combined with crossing vessels. All patients underwent modified transperotoneal laparoscopic dismembered pyeloplasty with pyelolithotomy. In cases with left lesion, an incision was made for the veress needle 5mm inferior to the costal margin in the left midclavicular line to establish pneumoperitoneum . A 12-mm camera port was placed 30 mm inferior to the umbilicus and 10 mm lateral to the border of left rectus muscle. Then, a 5 mm operative trocars was inserted at 30mm superior to the umbilicus 10 mm lateral to the border of left rectus muscle. Another 12 mm operative trocar was inserted at the opposite McBurney point. The last 5 mm operative trocar was placed at the veress needle point. After visualizing the pelvis and the proximal ureter at the lower pole of the kidney, a 1.0 cm transverse incision on the lower pole of the pelvis above the obstruction site was made. The Sun’s ureteroscope was introduced into the renal pelvis through the 1.0 cm transverse incision via the 12-mm trocar below the umbilicus. Stones in the renal pelvis and calyces were extracted with basket catheters and removed via the port. After the pyelo-nephroscopy, a modified transperitoneal laparoscopic pyeloplasty was made. A F6 double-J stent was inserted into the ureter during the surgery. Result: All surgeries were finished successfully without conversion. The surgical duration ranged from 111 to 185 min(mean 135 min). The estimated blood ranged from 10 to 50 ml(mean 38.8 ml). The hospital stay ranged from 3 to 7 days(mean 4 days). The intraoperative stone free rate was 100%(8/8). No perioperative complications occured. With the follow-up from 6 to 14.4 months(mean 8.9 months), there was no evidence of obstruction in all patients, as confirmed by symptoms or radiological improvement of hydronephrosis, and two patients found recurrence of renal calculi. Conclusions Our modified technique for transperitoneal laparoscopic pyeloplasty combined with deflectable tip rigid ureteroscope(the Sun′s ureteroscope) is a safe, effective method to manage ureteropelvic junction obstruction with renal calculi.