This study applied cumulative sum (CUSUM) analysis to evaluate trends in operative time and blood loss, It aims to identify key milestones in mastering extraperitoneal single-site robotic-assisted radical prostatectomy (ss-RARP). A cohort of 100 patients who underwent ss-RARP, performed by a single surgeon at the First Affiliated Hospital of Guangzhou Medical University between March 2021 and June 2023, was retrospectively analyzed. To evaluate the learning curve, the CUSUM (Cumulative Sum Control Chart) technique was applied, revealing the progression and variability over time. A cubic polynomial model was utilised to fit the non-linear data trends accurately. Key perioperative outcomes, such as operative duration and estimated blood loss, were assessed and compared between distinct learning stages to identify improvements and transitions during the surgeon's proficiency development. A total of 100 patients were included, with a mean age of 71.44 ± 5.46 years. The median operative time was 119.53 min (94, 144), and the best-fit equation for the CUSUM learning curve of operative time was y = 387.0373 - 3.4334x - 0.2982x