The tourism shoppers’ purchasing behaviors have critical effects to economies, but there are few of comprehensive review that integrates and synthesis the finding of literature on tourism purchasing behavior systematic from past, present and future perspective. As the international tourists consuming volume have decreased in average, the purchasing behavior has changed into online, planned characters especially under the conflict from COVID 19, this paper tries to find the way to solve this problem for the tourism retailing industries development and the market demand. The methods of this paper is to use the theory of tourist classification and duty-free products classification for research shoppers’ sample identification and duty free products wish lists audition, customers purchasing methods is to analyze the gap, Citespace is used here to fill the gap with domain knowledge and visualize the finding of 150 papers on tourism purchasing behavior published from 2010 to 2020. The finding of this research is: i) Lotte, King Power, Dubai international duty free can be Asia representative research shops, Chinese international tourists can be the research target group; ii) Fragrances & cosmetic, wines & spirits, fashion & accessories and personal luxury goods can be selected as the 4 duty free products categories; iii) Chinese tourism shoppers have the purchasing gap between oversea and domestic products, both those kinds of products can be acquired online and offline; iv) Multiple emergent themes in the existing corpus, the theory of planned behavior and online communication are the key domain knowledge to fill this gap. So, a questionnaire is urgent to design based on this research result to find out the decision tree nodes and then compose the decision-making model for duty free industry and tourism shoppers effectively.