Abstract: The present invention provides an interaction system and an interaction method thereof. The interaction system includes a display device, a detector, a database and a processing module. The display device plays a multimedia material. The detector acquires a comment that a user is watching the multimedia material. The comment includes a timestamp and an annotated position in the multimedia material. The database stores a plurality of interaction information related to the multimedia material. Each piece of interaction information has more than one index tag, and each of the index tag includes a timestamp and an annotated position in the multimedia material. The processing module searches for the index tag, matching the comment acquired by the detector, in the database, and then outputs the content of the interaction information corresponding to the found index tag to at least one electronic device.