Synopsis：The brain glymphatic system is a newly discovered anatomical system for removing waste products and maintaining homeostasis in the brain, and its damage is closely related to a variety of neurological diseases. The diffusion tensor image-analysis along the perivascular space (DTI-ALPS) technique has the advantage of being non-invasive and has been shown to be useful for assessing brain glymphatic system function. The purpose of this study is to use DTI-ALPS technology to evaluate the functional changes of the brain glymphatic system in patients with primary Parkinson's disease at different stages of the disease . Impact:DTI-ALPS technology is a potential imaging indicator for early diagnosis and monitoring of Parkinson's disease progression, and has definite value for clinical application. Purpose :the functional changes of brain glymphatic system in patients with Parkinson's disease at different stages of the disease will be investigated based on DTI-ALPS technology Methods:The clinical data of 100 patients with primary Parkinson's disease will be admitted to the First People's Hospital of Yunnan Province from March 2025 to April 2026 wil be prospectively collected, and they will be divided into two groups: 50 patients with early Parkinson's disease and 50 patients with late Parkinson's disease according to the Hoehn-Yahr Scale , and 50 healthy volunteers (HC) matched with them will be collected. All subjects will be scanned with a 3.0 T MRI system（MAGNETOM Prisma,Siemens Healthcare,Erlangen,Germany）.The scanning sequences included conventional MRI noncontrast and DTI sequences, which acquired images of b=0 s/mm² and b=1000 s/mm²4. FSL and ITK-SANP software will be used to delineate circular ROIs with voxel diameters of 5 mm in the projection fiber and contact fiber regions at the bilateral ventricular body level of the anisotropy score map, and the diffusivity of each fiber on the x, y, and z axes will be measured, and the DTI-ALPS index value will be calculated, and the one-way ANOVA wii be performed by IBM SPSS statistic 25.0 software, and the differences in the mean ALPS values of the left brain, right brain, and both sides of the subjects in the three groups will be compared. The correlation between the index and clinical data such as age, course of disease, Mini-Mental State Examination Score (MMSE), Montreal Cognitive Assessment Scale, Quality of Life Questionnaire for Patients with Parkinson's Disease (PDQ-39), Parkinson's Disease Non-motor Symptom Evaluation Scale (NMSS), Hamilton Depression Rating Scale score(HAMD), and Unified Parkinson's Rating Scale score (URPDS)will be analyzed.