Inclusion Criteria:  1. 18-70 years old 2. Patients who met the Rome IV diagnostic criteria of FD 3. Normal upper endoscopy and abdominal ultrasonography within one year.  Exclusion Criteria:  1, Patients with local or systemic diseases which may cause dyspeptic symptoms:  Known active peptic ulcer, cholecystitis, gallstone, gastrointestinal obstruction, gastroparesis, and etc. Known acute or chronic diseases of liver or kidney Obvious hematological abnormality, or endocrine and metabolic diseases suspected incomplete or complete bowel obstruction Known malignancy Other conditions which may be associated with dyspeptic symptoms (such as NSAIDs associated dyspepsia) 2, Pregnancy 3, Inability to give informed consent