provided are a method for viewing a presentation document in a mobile device and a system thereof . the method includes the steps of : determining an orientation of screen according to a sensing signal from a gravity sensor ; displaying slide thumbnails of the presentation document at the lower part of the screen in a horizontal arrangement when the screen orientation is portrait ; and displaying the slide thumbnails of the presentation document at the left part or the right part of the screen in a vertical arrangement when the screen direction is landscape . when a user opens a presentation document , the method for viewing a presentation document in a mobile device according to the present invention switches display mode of slide thumbnails in the presentation document automatically according to the screen orientation sensed by a gravity sensor , thereby being able to display the slide thumbnails in a more suitable manner according to different screen orientations , and facilitating the viewing and operation of the presentation by a user . the display manner in the method of the present invention better conforms to the psychological expectation of users , and can result in a better user experience .