Gili Trawangan Island has been designated as a tourism development area (Taman Wisata Alam Laut) by the government of Nusa Tenggara Barat through law (Perda) No.9 year 1989 dates 15 Augusts 1989. The aims of the research were to identify the potency of tourist attractions, to study both the internal condition (i.e. strength and weaknesses) and the external condition (i.e. opportunities and threats) and to study as well as to formulate the development strategy for Gili Trawangan island based on marine ecotourism.Method of data analysis used was descriptive qualitative and quantitative. Descriptive qualitative analysis is used to identify availability of facility support, potency, and tourism attraction, and also support existing stakeholder. Whereas in formulating strategy and design program of tourism development uses quantitative analysis constructively matrix IFAS, EFAS and matrix SWOT. Responder amount that taken base on purposive sampling amounts to 14 people. Research results indicated that existing potency of tourism attractions in Gili Trawangan Island are land natural beauty and undersea panorama with blue coral growth, culture, history, and tribe characters Mandar and Bajo Makasar. The result of internal environment score was high (3.04) and external environment was 3.00. So its position in matrix grand strategy stay in strong position by occupy cell 1 in matrix. Cell Position one shows strategy grows and constructs, growth passed by reachable concentration pass by vertical integration strategy is called grand strategy. Whereas special strategy cover programs strategy of tourism product development, strategy of security improvement and strengthen potency tourism destination that become features Gili Trawangan Island bases on marine ecotourism, Strategy of tourism facilities and basic facilities development, strategy of institute development and tourism human resources development (SDM), strategy of market penetration and promotion of tourism attraction, sustainable tourism planning and development strategy and community base development. Tourism development bases on marine ecotourism in Gili Trawangan Island have well prospective. Therefore, Action for promotion going concerns and synergic is required. In future coordination of society and government are expected in effort of sustainable development for Gili Trawangan Island. Keyword: Development, Potency and Tourism Attraction, Marine Ecotourism.