This trial aims to evaluate the clinical efficacy and safety of Zhizhu Kuanzhong Capsule in the treating patients with functional dyspepsia postprandial distress syndrome(FD PDS). Half of participants will receive Zhizhu Kuanzhong Capsule,while the other will receive a placebo.

Functional dyspepsia (FD) is one of the most common functional gastrointestinal disorders. Current data from clinical studies have shown that traditional Chinese medicine can obviously relieve clinical symptoms of patients with FD, and has special advantages and good clinical application prospects in the treatment of FD. Zhizhu Kuanzhong Capsule is mainly composed of the following 4 kinds of Chinese herbs: Rhizoma Atractylodis Macrocephala, Fructus Aurantii Immaturus, Radix Bupleuri and Fructus Crataegi. This trial aims to evaluate the clinical efficacy and safety of Zhizhu Kuanzhong Capsule in the treating patients with functional dyspepsia postprandial distress syndrome(FD PDS). This is a multi-center, stratified-block randomized, double-blind and placebo parallel-controlled trial. The comparison between the investigational drug and the placebo will be conducted with superiority design. About 480 subjects matched Rome IV diagnostic criteria for FD PDS will be enrolled. For each subject, this study includes a 0-2 week screening period, a 1-week run-in period, an 8-week double-blind treatment period, and a 4-week follow-up period. The drugs used in the clinical study (including investigational drug and placebo) will be supplied by Shuangren Pharmaceutical Co., Ltd. of Lonch Group.The quality standards and test methods for the placebo are consistent with those for the investigational drug, and the quality test meets the proposed quality standards. The selection and evaluation bias are controlled by means of strictly implementing randomized control blinded method etc, and the investigator will be trained on the consistency of scale evaluation.The electronic case report form (hereinafter referred to as eCRF) of this trial is created using the Medical Clinical Trial Data Management System (eCDMS3.0) for online data acquisition and management via the Internet. The data in the eCRF are from the original documents such as the original medical records and the physicochemical examination report sheets and should be consistent with the original documents. The response rate for functional dyspepsia VAS score will be compared between the test group and control group at 8 weeks after randomization.

Inclusion Criteria:

1. Meeting the Rome IV diagnostic criteria for functional dyspepsia-postprandial distress syndrome;

2. * At least 3 days during the one-week run-in period with VAS score ≥ 4 for major symptoms (at least one of postprandial fullness discomfort and early satiety) .

3. Age between 18 and 65 years old (including 18 and 65 years old), male or female, outpatients;

4. **Be able to discontinue prohibited medications that may affect the evaluation of the effectiveness, such as acid inhibition/antacids, prokinetic agents, non-steroidal anti-inflammatory drugs, anticholinergic agents, glucocorticoids, and therapeutic medication for H. pylori eradication.

5. Each subject is informed and voluntarily signed the informed consent form(ICF).

   • Subjects who entered the one-week run-in period are self-rated on the Visual Analogue Score (VAS) for the degree of discomfort with both symptoms of postprandial fullness and early fullness, with subjects indicating the degree of discomfort on a 10 cm ruler marked 0- "Asymptomatic or No Discomfort"and 10- "Extreme Severe or Extreme Discomfort"at its head and tail, respectively. The rating was made once a day and 7 days a week with scores of 0 to 10.

     • A 2-week wash-out period is required for patients taking prohibited medications prior to screening.

Exclusion Criteria:

1. Gastroscopic findings of gastric cancer, peptic ulcer, erosive gastritis (grade 2 or higher), moderate to severe atrophic gastritis, dysplasia, or other organ gastrointestinal disease.
2. Patients with a history of abdominal surgery (except for appendectomy and cesarean section).
3. Patients with immune system defects (such as leukaemia or cancer), or those who have been administered immunosuppressive agents or glucocorticoids within the past 3 months.
4. Patients who combined severe cardiac and pulmonary insufficiency, insufficiency of liver (ALT/AST > 1.5 times the upper limit of the normal value) and kidney insufficiency (BUN/Serum Creatinine > the upper limit of the normal value), abnormal of endocrine system( such as diabetes and thyroid dysfunction), abnormal hematopoietic system, and iron deficiency anemia as indicated on hematological examination.
5. Patients with severe anxiety and depression.
6. Patients with psychosis and mental retardation as well as language disorder precluding the ability of filling scales or recording symptoms.
7. Pregnant (a female of childbearing potential with a positive pregnancy test) or lactating females; or patients of childbearing potential without effective contraception.
8. Patients who are known to be allergic to the ingredients of this drug.
9. Patients who are suspected to have or indeed have a history of alcohol or drug abuse.
10. Patients who have participated in a clinical trial in the past 3 months.
11. Patients who are deemed by the investigator as being not suitable for participation in the clinical trial.