Humor study enjoys a long history with a variety of theories and methods. Among them, the pragmatic approach is a relatively new and vigorous perspective. Scholars have adopted the cooperative principle and relevance theory to explain humor. However, as to studying humor from the perspective of pragmatic presupposition, very few researches have been done in this regard. Such being the case, this paper will use presupposition as a tool to analyze humor in Lost in Thailand which is a sensational comedy in China. By analyzing cases from this film, the paper aims to explore how presupposition functions in the production of humorous effect, and to provide some new insights into humor study. Humor study enjoys a long history with a variety of theories and methods. Among them, the pragmatic approach is a relatively new and vigorous perspective. Scholars have adopted the cooperative principle and relevance theory to explain humor. However, as to studying humor from the perspective of pragmatic presupposition, very few researches have been done in this regard. Such being the case, this paper will use presupposition as a tool to analyze humor in Lost in Thailand which is a sensational comedy in China. By analyzing cases from this film, the paper aims to explore how presupposition functions in the production of humorous effect, and to provide some new insights into humor study.