There are many reasons for acidity in the mouth, most of which are poor gastrointestinal function, reduced oral salivary secretion, and female menopause. 1. Poor gastrointestinal function: most of the patients have indigestion, acid reflux, abdominal bloating, accompanied by acid in the mouth, spitting symptoms. 2. Low oral salivary secretion: patients with dry syndrome lead to dry mouth, sour and sweet mouth and other abnormal manifestations, and biochemical tests can be used for differential diagnosis. 3. Female menopause: when women enter menopause, due to endocrine disorders can also cause symptoms of sour mouth. Usually consume too much lemon, orange can also cause the symptoms of acidity in the mouth, the patient if usually appear acidity in the mouth should pay attention to, in the exclusion of physiological factors caused by the reason, go to the hospital for examination in a timely manner, so as to avoid delay in the treatment.