The research makes use of the Gray Relation Method to construct evaluation criteria of the grade-separated railroad in the urban area and analyzes those criteria in four aspects: transportation, society, economics and technology. Besides, it applies the Fuzzy Multi-Criteria Decision Making (FMCDM) theory, considering several conflicting evaluation criteria simultaneously and dealing with uncertain conditions, to evaluate the possibility of the grade-separated railroad. The theory makes decision process more reasonable and practical. There are several conclusions drawn from the empirical analysis of Tainan city and Pen-Tung county in this study. 1.Through a questionnaire survey, the implementation of grade-separated railroad in a city contributes mainly to the society aspect and secondly to transportation. In other words, though the issue of grade-separated railroad is raised originally for the traffic problem, it ultimately avails the renovation of the city. 2.As a whole, grade-separated railroad will improve the worsening traffic and land use problems in the urban area. It is hoped that the study will not only help the policy-making agency make decision under uncertain condition by applying the fuzzy theory but also provide the agency a reference to the evaluation of the grade-separated railroad.