This paper explored the tourist's behavior model of Ecotourism for constructing theoretical behavior model. The behavior model was constructed in which travel motivation was viewed as intermediated variable between environmental attitude, behavior, environmental attitude and satisfaction. By the collected data from protected area of Nan-Zon mountain of Kenting national park, the results showed that (1) environmental attitude significantly influenced travel motivation and then travel motivation also influenced behavior, (2) travel motivation influenced satisfaction, and (3) environmental attitude did not influence satisfaction. In a word, travel motivation worked as an intermediated variable in proposed model was validated.