Abstract: Objective:To analyze risk factors of breast ductal carcinoma in situ (DCIS) with microinvasion (DCIS-MI) and explore suitable axillary lymph node surgery treatment for patients with DCIS-MI. Methods:The clinical characteristics, such as age, menopausal status at diagnosis, size of breast mass, and pathology reports of 45patients with breast DCIS or DCIS-MI treated at Jinling Hospital, Medical School of Nanjing University from February 2013to February 2016, were retrospectively collected and analyzed statistically to deter -mine the risk factors associated with microinvasion.Results:Premenopause ( P=0. 006 ), tumor size ≥ 3. 15cm ( P=0. 006 ), and family his -tory of malignant tumor ( P=0. 002 ) were proven risk factors of DCIS-MI. Conclusion: Patients with clinical palpable axillary mass, pre  menopause, large breast mass, and family history of malignant tumor demonstrated high possibility of DCIS-MI. Hence, sentinel lymph node biopsy should be performed. Axillary lymph node dissection is highly recommended to patients whose main symptom is palpable axillary mass.