There are many possible factors that can cause blisters under the tongue, commonly including oral herpes, sublingual gland cysts, mucus cysts, etc. The specific need to go to the hospital for examination, clear diagnosis, and then targeted treatment. 1, oral herpes: is caused by viral infection of the oral mucosa disease, any part can occur in clusters of small blisters, easy to break, erosion. The treatment includes systemic and local antiviral therapy, using antiviral drugs such as acyclovir, ribavirin, etc. Local treatment, including compound borax solution with gargle, acyclovir ointment application, etc. It can also be combined with Chinese medicine and physical therapy. Daily maintenance of fluid balance, vitamin B and vitamin C supplementation, etc.; 2. Sublingual gland cyst: It is a retained cyst of the sublingual gland, a slightly blue, transparent mass on which the overlying mucosa can move. The sublingual gland can be removed surgically or the cyst can be removed by making an incision. If it is difficult to remove it completely, it can be sutured in the shape of a bag. 3. mucous cyst: the common disease sites are tongue, lower lip, and floor of mouth, etc. Mucous cyst is painless swelling, round, smooth surface, and higher than the mucosal surface. Surgical treatment can be performed to remove it. If the patient cannot cooperate with surgery, there is an option to inject drugs, such as tincture of iodine, into the cystic cavity with the aim of destroying the epithelial cells so that they lose their secretory function and no longer form cysts. Cryotherapy can also be applied to destroy its secretory function. Regardless of the cause of a vesicle under the patient’s tongue, the patient needs to get adequate rest and avoid staying up late, as well as eating a light diet to promote recovery from the disease.