H. pylori is a spiral-shaped, microaerobic bacterium that requires a very demanding growth environment. H. pylori parasitizes the gastric mucosal tissue and produces a variety of pathogenic factors that damage the gastric mucosa, causing diseases such as gastritis, peptic ulcers, and lymphoproliferative gastric lymphoma. A negative H. pylori indicates the absence of H. pylori infection. The detection methods for H. pylori infection mainly include rapid urease test, histological test, C13 or C14 urea breath test and serological test. The commonly used method is the C13 or C14 urea breath test, which requires the subject to be tested after two hours on an empty stomach or after a meal, by giving an oral urea capsule containing C13 or C14 marker, waiting 20 minutes to exhale again, and measuring the concentration of C13 or C14 in the exhaled gas to detect the presence of H. pylori infection. Sometimes there is no timely H. pylori infection, but the above laboratory tests still appear negative, i.e., false negative. Possible reasons include, if there is a recent application of antibiotics, bismuth, proton pump inhibitors and other drugs, the activity of H. pylori is lower and it is easy to have a false negative. Or if the amount of bacteria is relatively low, a false negative may also occur. To prevent H. pylori infection we should instruct them to establish a reasonable diet and structure, quit smoking and drinking, avoid intake of irritating foods, and keep their mouth clean. Keep the indoor environment clean, with appropriate temperature, fresh air and relaxed body and mind. If infected with H. pylori, patients should be instructed to take the correct antibacterial drugs and gastric mucosal protective agents, etc.