Acid in the mouth may be caused by the following reasons: First, it may be caused by excessive secretion of gastric acid, which occasionally refluxes into the esophagus, and may be caused by gastritis or gastric ulcer. May be liver depression spleen deficiency, can be under the guidance of Chinese medicine physician to take the liver and Qi medicine treatment; third, may be due to just eat sweets, sweets in the lactic acid and saliva reaction caused by, without treatment, immediately after eating rinse mouth can be effectively avoided; fourth, may be oral bacteria breeding caused by the unhygienic, pay attention to oral hygiene can be alleviated.