Objective: We designed a novel technique of suctioning flexible ureteroscopy with automatic control of renal pelvic pressure (RPP) by a patented system including a pressure-measuring ureteral access sheath (UAS) and an irrigation and suctioning platform. We sought to compare RPP values measured by the patented system and a nephrostomy catheter at different phases of flexible ureteroscopy. Materials and methods: Eight pigs with a total of 16 urinary tract systems were included. Via a subcostal incision a 6-F catheter was placed into the renal pelvis for RPP measurement by connecting to a pressure monitor. We then introduced the patented UAS retrogradely into the renal pelvis, through which the pressure was measured by the platform. RPP was measured at baseline period, irrigation and suctioning period, and therapeutic period. Results: Twelve renal pelves were successfully established models for pressure-measuring. Baseline RPP was 26.9+/-3.8 mmHg in the platform group and 26.3+/-5.2 mmHg in the nephrostomy group. There was no significant difference on RPP between the 2 methods either at irrigation and suctioning period (-5.21+/-2.11 vs. -3.59+/-1.45) or therapeutic period (-5.81+/-2.47 vs. -3.73+/-2.19). Conclusion: Renal pelvic pressure can be accurately and effectively monitored and controlled by our patented system.