A display device includes an image receiving unit, a power-saving control device, a display control unit, and a backlight module control unit. The power-saving control device judges whether or not received frames are still for a predetermined time. If the power-saving control device judges that the received frames are still for the predetermined time, the power-saving control device outputs a first control signal to the display control unit for controlling the display panel to perform power saving to reduce its power consumption while continuing displaying frames, and the backlight module control unit controls the backlight module to continue providing the backlight; while if the received frames are not still or are still for a time shorter than the predetermined time, the power-saving control device does not output the first control signal to the display control unit for controlling the display panel to perform power saving to reduce its power consumption.