Objective:To explore the method and experience of augmentation mammoplasty with autologous fat transplantation assisted by external expander.Methods:From January 2013 to December 2020, 352 female patients (698 breasts, 346 bilateral and 6 unilateral), aged from 18 to 55 years, with an average age of 41.5 years, were admitted to the Department of Cosmetic Surgery, Beijing Jingmei Medical Cosmetology Clinic. From 1-28 days before surgery, autologous fat transplantation was performed after wearing the dilator, and postoperative wearing of the dilator lasted from 1 to 24 months, with an average of 3.5 months.Results:The volume of fat transplantation per breast ranged from 150 ml to 460 ml, with an average of 320 ml. No obvious postoperative complications such as fat liquefaction, infection, intramammary induration and fat embolism were observed, and the postoperative appearance was lasting. The postoperative follow-up was conducted from 6 months to 7 years, and patient postoperative satisfaction rate reached 84.9% and doctors＇ satisfaction after surgery reached 82.1%.Conclusions:Augmentation mammoplasty with autologous fat transplantation assisted by external expander can effectively improve the appearance of breast morphology and contour defects and increase the survival rate of fat transplantation, which is worthy of clinical application.