With the rapid development of information technology and social media, The travel information increases. The people′s travel demands and preferences are gradually diversified and customized, so tourism information service has become a hot topic among researchers. Moreover, communities and user-operated media in social media have tremendous tourism information resources which can be employed in travel information mining based on social media. Since travel information is used for smart travel applications, it promotes the fast growing of internet-based tourism informatization. In this paper, the background of internet-based tourism inforamatization is discussed. Secondly, the characteristics of travel information in social media are analyzed. Then, some hot research topics in tourism applications are presented and discussed. Finally, the challenges of social media based travel data mining and applications are summarized, and some further research directions are explored.