1. Mammography: Mammography is a common method to diagnose breast cancer. The common breast diseases can be divided into lumps or nodular lesions, calcified shadows, thickened skin and ductal changes. The higher density of the mass and the presence of burr signs at the edges are very helpful in the diagnosis. When the burr is longer than the diameter of the lesion, it is called a stellate lesion. x-ray films often show a smaller mass than clinical palpation, which is also a sign of malignancy. The shape, size, and density of the calcified dots on the film should be noted, and the number and distribution of calcified dots should be considered. When the calcified spots are clustered, especially within 1 cm, there is a high possibility of breast cancer. If there are more than 10 calcified spots, the possibility of malignancy is high. Ultrasound can diagnose most of the breast lesions, especially for dense breasts and young women. In China, women have relatively little breast fat, so ultrasound is the best imaging tool of choice for this type of breast. Ultrasound scan can accurately identify whether the mass is cystic or solid, and can clearly show the changes in the direction of the ductal travel of the breast and the changes in the blood supply in the blood vessels, and understand the anatomical structure of the surrounding tissues of the breast, so as to determine the possible abnormalities of the breast, the specific location of the lesion and its relationship with the surrounding tissues. At the same time, ultrasound examination is superior in that it does not involve radiation damage and can be performed repeatedly and many times. 3.Thermal image examination: The images are used to show the temperature distribution on the body surface. Since the proliferating masses of cancer cells are rich in blood flow, the corresponding body surface temperature is higher than that of the surrounding tissues, and this difference can be used to make a diagnosis. However, this diagnostic method lacks exact image standard and the site of thermal abnormality does not correspond to the tumor, so the diagnostic rate is poor, and it has been used less and less in recent years. 4.Near infrared scan: The wavelength of near infrared ray is 600~900μm, which can easily penetrate soft tissues. The use of infrared light shows various gray shades through different density tissues of the breast, thus showing breast lumps. In addition, infrared light is sensitive to hemoglobin, and breast vascular shadows are clearly displayed. Breast cancer often has increased local blood flow and thickened blood vessels in the vicinity, and infrared light has a better image display, but the resolution of the lesion is poor and lacks specificity for benign and malignant lesions, so it has been used less and less in recent years. 5.CT examination: It can accurately show the location, size and shape of the primary foci, and clarify the degree of infiltration of the mass into the chest wall, as well as the posterior breast area, axilla, internal breast, and mediastinal lymph nodes. Disadvantages: Expensive and high radiation dose. It is good for the evaluation of preoperative staging of breast cancer, lesions located in areas not suitable for mammography, postoperative review of breast cancer, dense breast, breast edema or small development. 6.MRI examination: It can effectively make up for the shortage of other imaging examinations. For breast lesions that cannot be diagnosed by plain film or ultrasonography, especially for those who cannot find the primary lesion due to axillary lymph node metastasis, MRI can be used to accurately understand the size, number and margin of tumor lesions, show chest wall invasion, posterior sternum, mediastinum and axillary lymph node metastasis, and facilitate the staging of breast cancer and selection of surgical plan. MRI can guide puncture biopsy and interventional treatment, and can evaluate dense breast, local recurrence of breast cancer after surgery, as well as observe the location of implants, whether there are any omissions or complications and whether there are cancerous tumors in the residual breast tissue after mammoplasty, etc. Defects of MRI examination: it cannot show calcified foci, especially microcalcifications; the examination is expensive, takes a long time, and the image is easily disturbed by breathing movement. 7.Biopsy: The diagnosis of breast cancer must be established before treatment can be started, although there are many examination methods, so far only the pathological results obtained from biopsy can be the only basis for definite diagnosis. (1) Needle aspiration biopsy: Needle aspiration cytology is a simple, rapid and safe method that can replace some of the frozen sections of tissues, with a high positive rate of 80% to 90%, and can be used for cancer screening. If the clinical diagnosis is malignant but cytology reports benign or suspicious cancer, surgical biopsy should be chosen to clarify the diagnosis. (2) Excisional biopsy: This method is generally not advocated because it is easy to promote the spread of cancer tumor. It can only be considered for advanced cancer to determine the pathological type. (3) Excisional biopsy: Excisional biopsy is the removal of the lump and the surrounding tissues in a certain range when the lump is suspected to be malignant, and generally requires at least 1 cm from the edge of the tumor to be removed as completely as possible. Note: Breast ultrasound and mammography are known as the “golden combination” of breast cancer screening because of their low cost, low damage, easy operation and rich diagnostic information, and their complementary advantages.