Dry mouth is one of the main clinical manifestations of dryness syndrome, which is a chronic inflammatory autoimmune disease mainly involving exocrine glands. The common diagnostic criteria of oral involvement-related tests include salivary gland flow rate, parotid nuclear imaging, and labial gland biopsy. In recent years, with the development of science, in addition to the above common diagnostic criteria, parotid gland imaging, salivary gland CT, salivary gland MRI also have some value for clinical diagnosis, but the above methods have invasive, radiation, high price and allergic to contrast agent and other adverse factors, so the clinical application has some limitations, while high frequency, high resolution real-time salivary gland ultrasound with its convenient, safe, non-invasive advantages in the salivary gland The use of high-frequency, high-resolution real-time salivary gland ultrasound is playing an increasingly important role in the diagnosis of salivary gland diseases. In recent years, research on salivary gland ultrasound in the diagnosis of primary dry syndrome has been reported at home and abroad, but at present, it has not been used as a routine examination in China and has not been included in the diagnostic criteria of dry syndrome. The following is an introduction to the characteristics of salivary gland lesions in dry syndrome in the literature. The salivary glands in human body mainly consist of 3 pairs of large glands, namely parotid gland, submaxillary gland and sublingual gland, each of which has a duct leading to the oral cavity and secretes saliva. Since the sublingual gland is located under the mucous membrane of the floor of the mouth, it is difficult to be explored by ultrasound under normal circumstances. The salivary gland ultrasound in dry syndrome targets four glands of bilateral parotid and bilateral submandibular glands. The unique pathological change of salivary gland in this disease is the aggregated infiltration of a large number of lymphocytes, which is also the pathological basis of ultrasound images. The normal salivary gland ultrasound shows smooth and clear envelope, sharp edges, homogeneous parenchymal echogenicity, the same echogenic intensity as the thyroid, significantly higher than the subcutaneous fat echogenicity, and uniform attenuation in the far field. The echogenic lesions of salivary glands in dry syndrome are mainly of four types: (1) inhomogeneous type: due to the short duration of the disease and mild symptoms, the ultrasound only shows the unevenness of the internal dots of the gland, with no obvious changes in size and shape. (2) Nodular type: The sonogram shows hypoechoic nodules inside the gland, but there are different views on the cause of these sonographic features. The other believes that the destruction of the parotid gland in patients with desiccation syndrome is based on the infiltration of lymphocytes in the cystic dilated glandular ducts, which can be manifested as multiple cystic nodules in the gland. (3) Fibrotic type: Due to lymphocytic infiltrative lesions, it eventually leads to epithelial cell proliferation in local ducts and glands, followed by degeneration and atrophy, and the destruction is replaced by fibrous tissue proliferation, with ultrasound manifestation of glandular echogenicity enhancement, uneven distribution of light spots, and visible striations of intense light with echo. (4) Mixed type: the ultrasound performance in this type of gland has the characteristics of fibrosis and nodule-like echogenic changes. In conclusion, at present, there are different ways to express the characteristics of ultrasound of salivary gland lesions in dry syndrome at home and abroad, and its diagnostic value for dry syndrome needs to be further explored and studied, and whether it can be included in the diagnostic criteria is still inconclusive. Due to the safe, rapid and non-invasive characteristics of ultrasound examination, it can be used for the evaluation and diagnosis of lesions in patients with dry syndrome. At present, foreign studies have found that ultrasound exploration, as a convenient, inexpensive and non-invasive imaging technique, has important clinical significance for the early diagnosis of parotid lesions in SS patients, and is another alternative diagnostic tool.