Infarctions of breast fibroadenoma are rare, most reported cases occurred in women during pregnancy, lactation, postmenopause or following fine needle aspiration. We report a case of 35year old non-pregnant women, no previous needle biopsy and presented a giant, rapid-grow, spontaneous infracted breast tumor. The chief complaint was a rapidly enlarged, non-painful lump in her left breast in a six-month period. Malignant phylloid tumor was suspected on palpation examination and breast ultrasonography. Characteristics of history, physical examinations and radiological examination would mislead this kind of disease to malignant breast tumor. The pre-operation frozen sections is good guideline for surgical treatment.