Abstract: The invention proposes a system and method of a display device. When the distance between a user and the display device is too close or far, or the angle between the user and the display device slants too much, the display device sends out a command to inform the user to adjust the user's position while watching the display device. A method for the display device comprises following steps: a detecting device and an operating system calculating a relative position between the user and the display device, the operating system generating an warning command according to the relative position, a warning module receiving the warning command and afterward sending out the command, the command being sent to a display module, a motion-generating device and an audio device.