Mountain skiing has become a popular winter ecotourism activity in China. Studying the loyalty of eco-tourists from the perspective of tourist experience is important to the continued development of mountain ski tourism. Based on the flow experience theory, we developed and tested a structural equation model to examine relationships among flow experience, positive emotions and the loyalty of eco-tourists. Survey data from 324 eco-tourists with skiing experience at Daweishan Mountain Ski Resort was used for exploratory factor, confirmatory factor and path analyses. Results revealed five dimensions of flow experiences of eco-tourists: Concentration on task at hand, Loss of self-consciousness, Transformation of time, Autotelic experience, and Challenge-skill balance. As hypothesized, influences of Transformation of time, Autotelic experience and Challenge-skill balance on positive emotions were significant and positive. Concentration on task at hand, Autotelic experience, Challenge-skill balance and positive emotions positively influenced the loyalty of eco-tourists. Suggestions for developing ecotourism products are discussed such as designing a conductive environment to activate flow experience, providing personalized service to promote positive emotion, and developing experiential tourism activities.