In clinical practice, we often encounter patients asking which is more accurate, mammography or ultrasound? Some clinicians put all their hopes on mammography, thinking that as long as it is cancer, mammography can make the diagnosis. In fact, mammography + ultrasound should not be biased. It is because they are different aspects of breast tissue, just like the truth of “looking at the peaks and valleys, the height is different from near to far”. The mammogram is particularly suitable for soft tissue imaging, and with the advent of technology, there are now all-digital mammography machines, which have further reduced the amount of radiation and eliminated the need for special protective measures for medical staff. Since it is a radiation, it is particularly sensitive to calcification, and most early stage breast cancers (about 70%) show gravel-like calcification, which is why mammography is generally considered more accurate. However, early breast cancers (about 0.5 cm in size) and early breast cancers that do not show calcification require a combination of ultrasound examinations. In addition, the accuracy of mammography in diagnosing breast disease is affected by the degree of denseness of the breast. In young women, because of the dense glands and abundant fibrous tissue, the entire breast often appears as a dense shadow and lacks contrast. Therefore, the value of mammograms in women under 35 years of age is much less significant than in women over 35 years of age. Breast color ultrasound, also known as breast color Doppler ultrasound, can show the internal structure of breast tumor more clearly, observe the relationship between tumor and surrounding tissues, can observe the size, shape and edge of the lesion, and at the same time can better observe the amount and distribution of blood vessels inside and outside the tumor. It can measure the masses of 0.3~0.5 cm. Ultrasound diagnosis has the advantages of being easy and non-invasive. In view of the above features, the United Nations Health Organization has promoted breast screening worldwide by making mammography ultrasound and mammography together as the golden partner for breast screening.