The invention provides a content-based adaptive multimedia processing system and method for carrying out decision processing on results such as integration video analysis, audio analysis, word analysis and the like so as to convert multimedia contents comprising videos, audios and subtitles into multimedia contents which can be preferably watched on different play devices in the processing mode of giving consideration to the videos, audios and textual contents. Through the system, when original multimedia contents subjected to processing are played on the different playing devices such as mobile devices with different display sizes or computer program windows with different display proportions, video contents in which a user is interested are maximally maintained, so that important details in a picture are not lost because a screen is narrowed or proportion of the screen is changed, simultaneously important contents in the audios are prominently displayed, and display positions and display modes of the subtitles are regulated.