Objective: To investigate the clinical features, clinical progress and prognosis of mucinous carcinoma of the breast (PMC). Methods: 24 cases of mucinous carcinoma of the breast was analyzed by detailed histopathologic observation and immunohistochemical staining for estrogen receptor (ER), progesterone receptor (PR), HER-2, Ki-67, using Max Vision method. The follow up and clinical data were analyzed. Results: Eighteen cases were simple type of breast mucinous carcinoma, 1 cases of breast mucinous carcinoma with micro nipple structure, 6 cases were mixed type. Twenty-two cases were positive for ER, nineteen cases were positive for PR except one case of mixed type mucinous carcinoma were positive for HER-2. All cases of pure mucinous carcinoma were negative, there were statistically significant between PMC and MMC (P<0.05). Conclusion: The simple mucinous carcinoma of the breast which is composed of capillary rich fiber is characterized by the floating of the cell nests in the mucous lake. The sizes of the cell clusters are different, and the nuclei were not irregular, express for ER, PR positive and HER-2 negative. MUMPC of nuclear are pleomorphism and hobnail cells with the Her-2 positive. PMC with slow growth and low metastasis rate can be performed with breast conserving surgery. Mucinous micropapillary carcinoma of the breast (MUMPC) and mixed type of mucinous carcinoma of the breast are easy to be transferred. Modified radical mastectomy with postoperative radiotherapy and chemotherapy should be needed.