The purpose of this study is to investigate whether the eradication rate of H.pylori will be improved when adding fucoidan to the duplex scheme combination of amoxicillin and vonoprazan, and to explore the effect of fucoidan on gastrointestinal flora of patients.

After being informed about the study and potential risks, all patients giving written informed consent will undergo a 1-week screening period to determine eligibility for study entry. At week 0, patients who meet the eligibility requirement will be included in this simultaneous blind test. A total of 60 patients with HP infection were enrolled in this study. All patients were randomly divided into two groups according to the ratio of 1:1. Group A was given vonoprazan 20mg bid, amoxicillin 1000mg TID, fucoidan 1000mg bid for 14 consecutive days; Group B was given vonoprazan 20mg bid and amoxicillin 1000mg TID for 14 days. On the 10th and 14th days of treatment, the researchers will follow up the patients' adverse reactions and medication compliance. The feces of the subjects were collected one day before the treatment, and on the 14th and 44th days after the treatment; After 4 weeks of drug withdrawal, all subjects will be reexamined with 13C-UBT.

Inclusion Criteria:

1. Age 18-65 years old;
2. Patients diagnosed as HP positive;
3. Patients who have not received HP eradication treatment in the past, or who have failed in the early eradication but have not received eradication treatment within half a year;
4. Voluntarily participate in this trial and sign the informed consent form.

Exclusion Criteria:

1. Allergic to the study drug (penicillin allergy, etc.);
2. Patients with chronic gastritis and peptic ulcer;
3. Patients who have received HP eradication treatment within half a year;
4. Antibiotics and bismuth agents were used 4 weeks before the start of the study treatment, and histamine H2 receptor antagonists or PPIs were used 2 weeks before the start of the study treatment;
5. Use adrenocortical hormones, non steroidal anti-inflammatory drugs or anticoagulants;
6. History of esophageal or gastric surgery;
7. Pregnant and lactating women;
8. Suffering from serious accompanying diseases, such as liver disease, cardiovascular disease, lung disease, kidney disease;