Retrospective analysis ultrasound images and ultrasound diagnosis of 5 cases, which diagnosed as breast aggressive fibromatosis by pathology and misdiagnosed by ultrasound in our hospital, and analyze the cause of misdiagnosis. All the 5 patients had single breast disease, 3 cases on the left side and 2 cases on the right side. The diameter of the lesion was 20–48 mm. The two-dimensional ultrasound of the lesions showed irregular shape, unclear boundary, Internal low echo, slightly attenuated rear echo. Color Doppler showed a strip of blood flow around the lesion and inside, Adler blood flow classification II–III. The elastography score is 4 to 5 points. One patient underwent contrast-enhanced ultrasonography, which showed that the lesions began to strengthen slightly before the surrounding glands, and the enhancement morphology was slightly higher than the unevenness. The enhancement range was not significantly expanded, and no nourishing blood vessels were seen. In all cases, the ipsilateral axillary lymph nodes showed “false kidney sign” and no abnormal enlarged lymph nodes. Ultrasound diagnosis of 4 cases were considered for breast cancer, 1 case due to ultrasound contrast examination was considered that breast cancer and other diseases to be identified, and recommended medical examination. Breast aggressive fibromatosis is a rare disease. Ultrasound diagnosis is easily misdiagnosed as malignant lesions. In clinical work, when diagnose breast malignant tumors, especially in young patients, we need to consider the possibility of the disease by comprehensive analysis of various ultrasound image features.