Abstract: Parkinson's disease(PD) is a kind of degenerative disease afflicting middle-aged and older people, accompanied by abnormal D₂ receptor function resulted from dopamine deficiency. Raclopride is an ideal tracer because of its high selectivity and affinity to D₂ receptor. ¹¹C-raclopride PET can directly show the distribution and density of D₂ receptor on molecular level that it's of great importance in the analysis of the illness state and dopamine mechanism of sequential movement, movement-fluctuation complication, medicine and surgical therapy.