The main purpose of this paper was to apply the fuzzy analytic hierarchy process (FAHP) approach to explore key factors influencing the sustainable development of a green energy industry in Taiwan. Based on the literature and experts' opinions, a hierarchical structure with five assessment aspects and fifteen development factors was first constructed, and a FAHP algorithm model was then proposed. Finally, based on the AHP experts' questionnaires, we used the FAHP approach to evaluate the key factors. The results showed the following. (1) “Technology” is the most important aspect influencing sustainable development of green energy industry in Taiwan. (2) In order of relative importance, the top six key factors influencing sustainable development of green energy industry in Taiwan are “establishment of key technological capabilities,” “degree of integration of relevant laws and regulations,” “establishment of an industry chain,” “key raw materials and production equipment,” “protection of intellectual property,” and “preferential purchase price rates and various subsidies,” respectively.