A, the harm of H. pylori more than 50% of the world’s people are infected with H. pylori, and the infection rate in China is 40% -76%, the medical community has confirmed that H. pylori is the cause of chronic gastritis, duodenal ulcer and gastric ulcer culprit, and is an important cause of gastric cancer. Second, the superiority of C13 urea breath test to detect H. pylori There are various methods to detect H. pylori, the specificity and sensitivity of C13 urea breath test method is very high, non-invasive, painless, simple method, reliable results, can reflect the current infection of H. pylori in the stomach. Third, precautions 1, what needs to be done before the examination (1), the examiners overnight fasting, fasting water for more than 8 hours. (2), patients who are ready to perform breath test to avoid the effect of certain drugs on the test, patients need to be free of acid suppressants, bismuth and other drugs for at least 2 weeks and antibiotics for 4 weeks before the test. (3), should maintain a quiet (sitting or lying position is acceptable) state throughout the examination, avoid strenuous activities during the examination, which may affect the results.