Calcifications are one of the common imaging manifestations of breast cancer. Certain specific forms of calcification are risk factors for breast cancer. Clusters of microcalcifications are often the only mammogram sign of early breast cancer. The nature and extent of the lesion can be reflected by the shape, size, number and density of microcalcifications. Microcalcifications can be located in or around the lump, with a total number of 6 to 15, with uneven density and varying size. Mammography can improve the diagnosis rate of occult cancer, microscopic cancer and early cancer. The high number of microcalcifications per unit area of breast malignant lesions may be due to a combination of causes such as necrosis of cancer tissue and secretion of cancer cells. The different densities and sizes among calcification sites may be due to the different lengths of time of calcium salt deposition, with the calcifications formed first over time being relatively denser and larger in size. Compared with benign calcifications, the average density of malignant calcification clusters is lower, and the density and size are of greater value in differentiating benign from malignant breast disease. The distribution of microcalcifications in mammograms seems to be irregular, but when pathology reveals that the cancer occurs in the terminal ducts, calcifications may be located in large areas of necrotic tissue or among cancer cells, or they may exist in the superior ducts to which they belong or in the bifurcation of the ducts or in the lumen of the adjacent alveoli. The regional calcification of cancer foci may be of fine sand or mixed type, and the intra-ductal calcification may be of worm type, which may be related to the abnormal secretion of tumor draining along the duct. When the cancer is located in larger ducts, calcifications away from the lesion are often located in the peripheral next-level ducts and are mainly of fine sand type, which may be produced by abnormal metabolites of cancer cells or the reflux of cancer cells stimulating the terminal ducts and glandular alveoli. The large number, fine particles and rough edges, which can be located inside or outside the block shadow, suggest malignancy.