Objective To evaluate the ¹⁸F-N-3-fluoropropyl-2β-carbomethoxy-3β-(4-iodophenyl) nortropane (¹⁸F-FP-β-CIT) dopamine transporter (DAT) PET imaging in diagnosing Parkinson’s disease with early stage and assessing the severity of their disability. Methods 4 healthy controls, 21 parkinsonian patients with early stage and 10 parkinsonian patients with advanced stage were studied, the ratio of [region of interest (ROI) - cerebellum]/cerebellum was measured and compared. The correlation between DAT binding in striatum and unified Parkinson’s disease rating scale (UPDRS) motor scores was also determined. Results In patients with early stage (Hoehn and Yahr stage Ⅰ~Ⅱ), the DAT binding uptake in the caudate, anterior putamen and posterior putamen was significantly reduced to 71.8%, 43.8% and 23.6% of the control value respectively, and more pronounced reduction of the uptake was found in the striatum contralateral to the predominant symptoms. Compared with age-matched controls, there was a significant reduction of DAT binding in the ipsilateral (preclinical) striatum of hemi-parkinsonian patients with Hoehn and Yahr stage 1 or 1.5. In the patients with advanced stage, the corresponding figure were further reduced to 51.9%, 31.8%, 15.8%. The DAT binding uptake in striatum of all parkinsonian patients showed significantly negative correlation with UPDRS motor scores, especially in the subregion of posterior putamen. Conclusion 18 F-FP-β-CIT DAT PET imaging is helpful in diagnosing Parkinson’s disease with early stage and assessing the severity of their disability.