To investigate the clinicopathological features, immunophenotype, special staining features and differential diagnosis of primary acinic cell carcinoma (ACCA) of the breast, a case of primary ACCA of the breast was analyzed by HE, immunohistochemistry and special staining, and the related literature was reviewed. The patient, a 41-year-old female, was treated for a mass in her left breast. Microscopically, the tumors had various morphologies, such as nest-like, alveolar, tubular or microadenoid structures, and infiltrated into the surrounding fibrous and adipose tissues. Tumor cells with nest-like patches had obvious atypia and high mitotic activity, with higher nuclear grade, coarse granular cytoplasm and basophilic cytoplasm, while those with better alveolar differentiation had mild morphology and homogeneous granular cytoplasm. The eosinophilic colloidal secretions in the cavity can be seen in the area of microadenoid structure, which is similar to microadenopathy. Immunohistochemistry showed that S-100, CK7 and EMA were positive, while ER, PR, HER-2 and myoepithelial markers, such as CK5/6, p63 and Calponin were negative. PAS staining was positive. ACCA of the breast is very rare. It is very similar to ACCA of the salivary gland. Compared with triple negative invasive breast cancer, it has a better prognosis, but its histogenesis still needs further study to clarify and provide strategies for better treatment.