Breast cysts are a common breast disease that occurs in pre-menopausal and peri-menopausal women, and whether they are cancerous or require surgery is a big concern for many young and middle-aged women. In fact, most of the breast cysts are benign and do not increase the risk of breast cancer, so they do not need surgery and even do not need any treatment except for regular review. Breast cysts are classified as 1. Simple cysts: they are cysts with clear borders, posterior echogenic enhancement, no internal echogenicity, solid occupancy and blood flow signal as shown by ultrasound. Most of them are of this type clinically. 2.Complex cyst: It is a cyst with ultrasound showing low echogenicity but no solid occupancy, thick-walled cyst or thick fluid cyst, and no internal blood flow signal. Malignancy in complex cysts is very rare (0.4%), and usually confirming diagnosis by puncture or imaging and clinical observation can be performed. 3. Mixed cysts: refers to cysts with a wall of more than 0.5 mm and cysts containing both fluid and solid, and B ultrasound shows both echogenic and echogenic changes. The incidence of malignant lesions in mixed cysts is 20%-43%. II. Indications for surgery of breast cysts: Surgery is needed when breast cysts are accompanied by the following conditions 1.Simple cyst puncture fluid is bloody and the lesion does not disappear after puncture or cytopathology suggests the presence of cancer cells. 2.Simple cyst recurs after repeated non-surgical treatment (more than 3 times), and imaging review reveals suspicious lesions or the patient himself wants to operate. 3.Progressive enlargement of complex cyst, or imaging features suspecting malignant lesion, or ultrasound cannot determine whether there is solid lesion in between can be considered for surgery. 4.Mixed cysts.