Introduction: The safety and effectiveness of percutaneous nephroscopic surgery without artificial hydronephrosis remain controversial, and there are few relevant studies. This retrospective study aimed to compare the efficacy of two different methods of eliminating and creating artificial hydronephrosis in percutaneous nephrolithotomy (PCNL) in the oblique supine position. Methods: This is a retrospective study. A total of 162 patients who underwent PCNL in an oblique supine position at our hospital were divided into two groups according to the surgical method: the free artificial hydronephrosis group (group A) and the artificial hydronephrosis group (group B). Group A was directly treated with PCNL under ultrasound guidance, and group B was treated with artificial hydronephrosis before PCNL. Several outcomes were measured, including procedure time, stone clearance rate, and incidence of complications. Results: The procedure time in group A lower than that in group B, and the incidence of sepsis was significantly lower in group A than in group B (p < 0.05). There was no statistical difference in stone clearance rate, success rate of primary establishment of puncture channel, unilateral change in perioperative red blood cell count, change in perioperative renal function, and perioperative complications (except sepsis) between the two groups (p > 0.05). Conclusion: For experienced physicians, PCNL without artificial hydronephrosis in an oblique supine position can be attempted to reduce the number of surgical steps without affecting the stone clearance rate and increasing the occurrence of complications.