An organic light emitting diode (OLED) display device supporting a variable frame mode includes an OLED display panel, a data driver configured to provide a data signal to the OLED display panel, a scan driver configured to provide a scan signal to the OLED display panel, an emission driver configured to provide an emission control signal to the OLED display panel, and a controller configured to control the data driver, the scan driver and the emission driver, to count a time of a current frame, and to control the emission driver to decrease an off period ratio of the emission control signal as the counted time of the current frame increases.