The pH of H. pylori refers to the result of the breath test, in which the C13 breath test negative pH is 0~4bpm and the C14 breath test negative pH is usually 0~100bpm. Breath test is divided into C13 and C14 breath test, in which C13 breath test negative pH is 0~4bpm, exceeding the above value suggests positive; C14 breath test negative pH is 0~100bpm. It should be noted that, within 4 weeks of the breath test can not take antibiotics (such as amoxicillin, cefuroxime, etc.), bismuth (such as bismuth potassium citrate) and other drugs; 2 weeks can not take acid-suppressing drugs (pantoprazole, omeprazole, etc.), all of the above drugs may lead to false-negative breath test. If the result of C13 or C14 breath test is positive suggesting that there is Helicobacter pylori infection, it is recommended that the patient go to the hospital in a timely manner and take medication under the guidance of the doctor.