Salivary glands, also known as salivary glands, are exocrine glands that secrete saliva through the vesicles and discharge it into the oral cavity through the ducts to keep the mouth moist. More than 99% of saliva is water, and the saliva produced in 24 hours can reach 600-1000 ml. each ml of oral fluid contains 6×103-600×103 squamous cells; 25×103-650×103 white blood cells; 600-700 bacteria. -700. Saliva is a mixture produced by the salivary glands. Humans have three pairs of large salivary glands, the parotid, submandibular and sublingual glands. These glands have a long ductal system to discharge saliva, of which 90% is produced by the parotid and submandibular glands, 5% by the sublingual glands, and 5%-10% by the small intraoral salivary glands. The vast majority of saliva is produced daily as a result of stimulation. It is mainly gustatory and chewing during feeding. The composition of the fluid secreted by the major salivary glands varies. The parotid gland is mainly plasma and rich in amylase, the submandibular gland secretes more mucus components, and the sublingual gland produces mainly mucus. Saliva also contains salivary proteins, which adhere to the teeth and oral mucosa surface and play a protective role. Small salivary glands are mainly distributed in the oral mucosa and submucosa, and can be divided into lacrimal glands, palatal glands, lingual glands, posterior molar glands, and buccal mucosal glands according to where they are located. The parotid glands are the largest pair of salivary glands in the human body, soft and light yellow in color, the size of parotid glands varies from person to person, for the same body, the left and right are basically symmetrical. The submandibular glands are the second pair of large salivary glands, the size of a walnut, and are mixed glands with a predominantly pulpy nature. They are located in the submandibular triangle at the lower edge of the mandible. The sublingual gland is the smallest of the three pairs of major salivary glands, shaped like an almond, and is a mucus-based mixed gland located in the sublingual fossa surrounded by the mucosa of the sublingual floor and the mandible. The salivary glands are a group of important glands that are essential for maintaining the normal functions of the oral cavity and digestive system, such as feeding, digestion, and speech. The occurrence, development, manifestation and management principles of salivary gland diseases have their own unique rules. There are many kinds of salivary gland diseases, including inflammation, injury, tumor, tumor-like lesions, autoimmune diseases and the manifestation of certain diseases in the salivary gland. 1. Salivary gland inflammation refers to various acute and chronic inflammatory diseases occurring in the parotid, submandibular and sublingual glands, including salivary stone disease (with gland inflammation), acute suppurative parotitis, chronic parotitis, submandibular gland inflammation, and epidemic parotitis. Treatment for these diseases is mainly targeted anti-inflammatory treatment, with rest and nutritional support, maintaining oral hygiene, and surgery if necessary. 2, salivary gland injury is due to external force caused by the gland or duct injury, mainly in the parotid gland, because the parotid gland and its duct is located in the subcutaneous cheek, the location of superficial easy to be injured. The submandibular and sublingual glands are less likely to be injured because of their more protected location. Most salivary fistulas occur after injury to the parotid gland and its ducts, occasionally after congenital salivary fistulas or secondary infections. It can be treated by surgical intervention. The incidence of tumors in parotid gland is the highest, accounting for about 80%, followed by submandibular gland. There are no exact statistics on the incidence of tumors in China, but according to the statistics of dental hospitals in Beijing, Shanghai, Chengdu and Xi’an, salivary gland tumors account for about 20% of oral and maxillofacial tumors, which is not uncommon. Salivary gland tumors are common in people above 40 years old, with women slightly more than men, while malignant tumors are common in men, mostly above 50 years old. Among parotid tumors, benign accounts for about 80% and malignant accounts for 20%; among submandibular gland tumors, the proportion of benign and malignant tumors is basically close; among sublingual gland tumors, the proportion of malignant tumors is as high as 90% and benign accounts for only 10%; among small salivary gland tumors, malignant tumors also account for the majority, more than 60%; common benign tumors include pleomorphic adenoma, adenolymphoma, basal cell adenoma, papillary cystic adenoma, etc.; common malignant tumors include mucous epithelial tumor, mucosal lymphoma, mucosal cystic adenoma, etc. malignant tumors include mucinous epidermoid carcinoma, adenoid cystic carcinoma, malignant mixed tumor, adenoid blast cell carcinoma, adenocarcinoma, squamous cell carcinoma, etc. Treatment mainly relies on surgery. 4.Tumor-like lesions include benign hypertrophy of salivary glands, necrotizing salivary gland tissue chemosis, salivary gland cysts, etc. The common clinical sublingual cysts belong to exudative cysts, which are benign lesions and can usually be treated well by surgical excision. 5, autoimmune diseases mainly refers to the progressive destruction of exocrine glands due to various immune diseases, resulting in dryness of oral mucosa, conjunctiva and other parts of the mucosa. For this type of disease, the main treatment is symptomatic, the body immune state conditioning, if necessary, with surgery. 6, the performance of certain other diseases in the salivary gland, such as cystic lymphatic hyperplasia in AIDS patients, chronic sclerosing submandibular adenitis, malignant lymphoma of the salivary gland, etc.. The main thing is to diagnose clearly and treat for the whole body condition. For the diseases occurring in the salivary gland area, it is required to pay enough attention to a clear diagnosis and reasonable treatment, which can generally obtain a better treatment effect.