An organic light-emitting diode (OLED) display device capable of reducing power consumption within a range in which an image quality is not lowered, and a method of driving the OLED display device. The OLED display device includes: an image analyzer for obtaining an emission ratio and a saturation of an input source image, the emission ratio indicating light-emitted degrees of pixels constituting the input source image; an emission ratio adjuster for adjusting the emission ratio according to the saturation; a brightness adjuster for adjusting the brightness of the input source image according to the adjusted emission ratio; a data driver for establishing a data voltage of a data signal corresponding to the input source image based on the adjusted original brightness; and a pixel unit including an organic light-emitting diode (OLED), the pixel unit being configured to establish a driving current according to the data voltage.