The invention provides a display device and an operating method thereof so as to solve the problem that the display device cannot automatically enter a sleep mode, and save energy. The display device comprises a display panel, a backlight module, an image acquisition unit and a control unit, wherein the image acquisition unit is used for acquiring a user image in real time and transmitting the user image to the control unit; and the control unit is used for receiving the user image and analyzing the user image to determine user state information, and when the user state information meets the preset conditions, the display device is controlled to enter a power-saving state.