The goal of this clinical trial is to explore raise-bed training Orthostatic Hypotension in Parkinson's Patients. The main question it aims to answer is: Can raise-bed training improve Orthostatic Hypotension in Parkinson's Patients. Patients will be randomly allocated into the control group or the experimental group, all under rehabilitation treatment, the experimental group will be given raise-bed training. The study lasts 21 days for each patient. Researchers will compare Orthostatic Hypotension Questionnaire, Orthostatic Grading Scale, Composite Autonomic Symptom Scale 31 to see if raise-bed training can help improve the symptom.