Mouth has been secreting saliva may be physiological phenomenon, may also be oral herpes simplex, oral ulcers, as well as dental caries and other diseases. 1. Physiological phenomenon: If infants and young children appear to inhibit the secretion of saliva performance is considered to be due to the imperfect development of the swallowing function, and salivary glands after the development of salivary secretion due to excessive. This is a normal physiological phenomenon, can not be dealt with. 2. Oral herpes simplex: oral herpes simplex may be caused by type I simplex virus infection, the patient will not only appear to have been the secretion of saliva, but also fever, sore throat, oral cluster of blisters, lymph node swelling and other symptoms. 3. Oral ulcers: the cause of oral ulcers is still unclear, may be caused by immune factors, mental stress, heredity and so on. The patient’s oral mucosa will appear round or oval depression of the ulcer surface, if the ulcer surface is stimulated, the patient will have been drooling symptoms, as well as oral pain and other manifestations. The mouth secretes saliva all the time may also be caused by dental caries, periodontitis, lingual inflammation and other diseases. If it is accompanied by crooked corners of the mouth and slurred speech, it may also be caused by cerebrovascular disease. It is recommended that the mouth has been in the secretion of saliva need and medical treatment, if it is caused by physiological factors do not need to be treated, if it is caused by disease, it is necessary to address the cause of the treatment.