Oral odor can be seen in the following reasons: first, infected with Helicobacter pylori, usually gastroenterology after infection with Helicobacter pylori can appear to have special bad breath, indigestion and other clinical manifestations, this is because Helicobacter pylori parasites in the stomach, can produce toxins, resulting in the patient’s self-conscious bad breath taste, but also the clinical findings of the oral cavity odor is a common factor. Second, if the patient has indigestion or constipation symptoms, there will also be oral odor, third, is related to the patient’s teeth and gums itself has a disease. If a periodontitis or gingivitis patient, due to oral disease can also lead to the emergence of oral odor and bad taste. Therefore, if there is a bad taste in the mouth, it is recommended to go to the gastroenterology department first to rule out whether there is Helicobacter pylori infection and the corresponding digestive tract diseases, and finally can also go to the dentistry department to carry out symptomatic diagnosis and treatment.