Abstract: Objective To explore the efficacy of flexible ureteroscopy(F-URS)for the treatment of renal and upper ureteral calculi smaller than 2 cm based on the mode of enhanced recovery after surgery(ERAS). Methods A total of 80 patients with renal and ureteral calculi(smaller than 2 cm)who were selected for surgical treatment were randomly divided into ERAS group and the control group according to random number table method. All the patients were given F-URS, the control group(n=40)was given traditional perioperative management, ERAS group(n=40)was given ERAS surgical treatment process. The perioperative relevant indicators, the body's stress response and postoperative complications were comparatively analyzed. Results Compared with the control group, ERAS group had significantly shorter time of first feeding, removal time of calculi and postoperative hospital stay(P<0.05). Compared with operation before, the ERAS group and the control group showed significant differences in leukocyte count(WBC), C reactive protein(CRP )at 1 h after operation(P<0.05). At 1 h after surgery, each stress response index of the two groups increased to different degrees, and then began to decrease at 1^st day of surgery(P<0.05). The ERAS group had significantly lower indexes at 1^st day and 3^rd day after surgery than the control group(P<0.05). The incidence of postoperative complications in ERAS group was significantly lower than that in the control group(P<0.05). Conclusion F-URS for the treatment of renal and upper ureteral calculi smaller than 2 cm based on the mode of ERAS, can shorten the length of hospital stay, reduce stress response and perioperative complications.