1 INTRODUCTION
With the rapid development of Social Network Service (SNS) applications, Internet has become an important channel for people to get information and to express their opinions. Because of a wide variety of multimedia data in SNS [1], the fusion of all kinds of media form information from different sources using a cross-media data mining methods is very important for topic analysis and hot topic tracking, which is also an important issue to monitor emergency events in complex decision-making environment . It's needed to adopt a cross-media mapping method to extract data from all possible media, converted to a unified semantic space for processing. In this way, more knowledge reflecting current hot events can be discovered, and the status of the events can be accurately assessed too.