Objective: To analyze the clinical effect of endoscopic incision under the axilla combined with ultrasonic knife in subpectoral fascia-level breast augmentation surgery. Methods: 80 patients undergoing breast augmentation surgery were divided into the observation group (40 cases, endoscopic incision under the axilla + ultrasonic knife + subpectoral fascia-level breast augmentation surgery) and the control group (40 cases, traditional breast augmentation surgery). The clinical effects of the two groups were compared. Results: The operation time, intraoperative blood loss, postoperative hospital stay, VAS scores at 24 hours and 48 hours after surgery, and the incidence of complications in the observation group were all less than those in the control group (P < 0.05). The excellent rate and satisfaction score of the observation group were higher than those of the control group (P < 0.05). Conclusion: The application of endoscopic incision under the axilla combined with ultrasonic knife in subpectoral fascia-level breast augmentation surgery can shorten the operation time, reduce intraoperative blood loss, alleviate postoperative pain, accelerate postoperative recovery, achieve better clinical efficacy and lower complication rate, and improve the overall satisfaction of patients.