A display system with automatic brightness adjustment, comprising: a display device having a screen; a lamp disposed above the screen and configured to provide the screen with an extra light source in addition to ambient light; a first optical sensor configured to detect an ambient light luminance when the lamp is turned on, wherein the first optical sensor is disposed at a location which is unaffected by luminance of the lamp; a second optical sensor configured to detect an overall brightness of the display device, wherein the second optical sensor is disposed on the display device; and characterized by: a controller configured to: acquire the ambient light luminance from the first optical sensor; adjust brightness and color temperature parameters of the screen according to the acquired ambient light luminance; determine whether a brightness and a color temperature of the screen match predetermined values, and, if not so, repeat said adjusting and determining until the brightness and the color temperature of the screen match said predetermined values; in response to determining that the brightness and the color temperature of the screen match said predetermined values: the overall brightness from the second optical sensor; adjust brightness and color temperature parameters of the lamp according to the acquired overall brightness; and determine whether the brightness and the color temperature of the screen match predetermined values, and, if not so, repeat said adjusting of the lamp and determining until the brightness and the color temperature of the screen match said predetermined values. a display device having a screen; a lamp disposed above the screen and configured to provide the screen with an extra light source in addition to ambient light; a first optical sensor configured to detect an ambient light luminance when the lamp is turned on, wherein the first optical sensor is disposed at a location which is unaffected by luminance of the lamp; a second optical sensor configured to detect an overall brightness of the display device, wherein the second optical sensor is disposed on the display device; and characterized by: a controller configured to: acquire the ambient light luminance from the first optical sensor; adjust brightness and color temperature parameters of the screen according to the acquired ambient light luminance; determine whether a brightness and a color temperature of the screen match predetermined values, and, if not so, repeat said adjusting and determining until the brightness and the color temperature of the screen match said predetermined values; in response to determining that the brightness and the color temperature of the screen match said predetermined values: the overall brightness from the second optical sensor; adjust brightness and color temperature parameters of the lamp according to the acquired overall brightness; and determine whether the brightness and the color temperature of the screen match predetermined values, and, if not so, repeat said adjusting of the lamp and determining until the brightness and the color temperature of the screen match said predetermined values. acquire the ambient light luminance from the first optical sensor; adjust brightness and color temperature parameters of the screen according to the acquired ambient light luminance; determine whether a brightness and a color temperature of the screen match predetermined values, and, if not so, repeat said adjusting and determining until the brightness and the color temperature of the screen match said predetermined values; in response to determining that the brightness and the color temperature of the screen match said predetermined values: the overall brightness from the second optical sensor; adjust brightness and color temperature parameters of the lamp according to the acquired overall brightness; and determine whether the brightness and the color temperature of the screen match predetermined values, and, if not so, repeat said adjusting of the lamp and determining until the brightness and the color temperature of the screen match said predetermined values.