Parkinson's disease(PD) may cause the autonomic nervous system's improper functioning, which is responsible for regulating the intestinal tract movement. A certain degree of degeneration of digestive system function can cause PD patients to constipation symptoms. Studies have shown that up to 63 percent of people with Parkinson's disease experience constipation. What is more, medications for PD, including levodopa and dopamine agonist, can also cause constipation. In recent years, an increasing number of studies have been conducted to investigate gut microflora and their influence on the central nervous system. Furthermore, some studies of Parkinson's disease have confirmed that gut microflora plays a vital role in the occurrence and development of Parkinson's disease.

The purpose of this study is to evaluate the efficacy and safety of fecal microbiota transplantation in the treatment of constipation symptoms in patients with Parkinson's disease receiving a steady dose of levodopa. We will also analyze intestinal flora diversity in patients with Parkinson's disease with constipation. The investigation of the gut microbiome may emerge as a new therapeutic measure to treat constipation associate with Parkinson's disease.

Inclusion Criteria:

• Between 18-75 years of age
• Signed informed consent form
• Clinical diagnosis of Parkinson's disease (according to 2016 edition of Chinese Parkinson's disease diagnostic criteria)
• Parkinson's disease duration of 1 year or more
• Hoehn & Yahr stage 1-4 (including)
• Patients have following 2 or more symptoms, which appear for at least 6 months and exist in recent 3 months: A. at least 25% of defecation feel strenuous; B. At least 25% of defecation was not massive or hard; C. at least 25% of defecation had incomplete feeling; D. at least 25% of defecation had anorectal obstruction; E. at least 25% of defecation needed manual assistance; F. defecation less than 3 times a week, with or without abdominal pain
• Patients are taking oral L-dopa (with or without Benserazide, carbidopa, and O-methyltransferase inhibitors) at least 4 weeks, and be able to tolerate a steady dose of dopamine agonists, monoamine oxidase B inhibitors, anticholinergics, and / or adamantine.
• Patients are taking stable dosage of anti-PD drugs, antidepressant drugs and antipsychotics for more than 1 month.
• Be able to tolerate the FMT infusion method such as endoscopy, colonoscopy, capsule, nasoduodenal tube insertion, etc.
• Be able to receive follow-up visit, follow-up examination and specimen collection on time

Exclusion Criteria:

• Patients with Parkinson's syndrome and Parkinsonism plus syndrome
• History of cerebrovascular accident, brain injury, epilepsy and other brain injury
• The "opening" stage was Hoehn & Yahr 5
• Patient received neurosurgical intervention or stereotactic brain surgery for Parkinson's disease
• Patients with organic lesions of digestive tract
• Patients had major abdominal surgery
• History of infectious diarrhea and took antibiotics in recent 2 weeks
• Patients infected with Clostridium difficile and other pathogens
• Patients with HIV or compromised immune system (such as congenital immunodeficiency or currently taking immunosuppressive drugs)
• Patients with uncontrollable basic diseases of digestive system
• Patients could not fully understand and sign the informed consent form
• Patients who were not considered suitable for inclusion in the study