Taiwan government has been actively promulgating the idea of ecological construction methods recently; however most of the past efforts focused on developing new techniques rather than on evaluating alternatives. To simultaneously ensure ecology preservation and to meet engineering requirements, it is a complicated decision-making process for selecting a desirable ecological slope method; while considerable losses derived from an unseemly alternative may incur. This paper proposed a modified fuzzy analytical hierarchy process (FAHP) which can systematize and ease this complex process so that it can be used to assist the project planner towards a correct decision. This method can effectively deal with uncertainties associated with experts' linguistic assessments for the relative weights of paired criteria under varied degrees of believe (α value). A case study was presented to explain the use of FAHP and demonstrate the effectiveness and practicality of this approach.