Bringing self-generated litter down the mountain is an emerging pro-environmental behavior to solve the problem of trail's litter management in China. This study is the first attempt to explore a theoretical explanation model that explicates tourists' complex intention-forming process for engaging in it. The study extended the Theory of Planned Behavior model, including three additional explaining variables (environmental theory knowledge, environmental practice knowledge, and incentive measures), as well as a moderator of travel companions between subjective norm and the behavioral intention....