An organic light-emitting diode (OLED) display device can include a pixel and a data driver. The pixel includes a driving thin film transistor (TFT) to drive an OLED element, a first switching TFT to connect a data line to a gate electrode of the driving TFT, a second switching TFT to connect a reference line to a source electrode of the driving TFT and a capacitor connected between the gate electrode and the source electrode of the driving TFT. The data driver includes a first amplifier to drive the data line with a reference voltage or a data voltage, a second amplifier to drive the reference line with an initialization voltage, and a third amplifier to sense a voltage of the reference line and supply a reference sensing voltage to the second amplifier, in which the reference line voltage is based on a threshold voltage of the driving TFT.