A method for driving an organic light emitting display (OLED) panel having a plurality of organic light emitting diodes is provided. The organic light emitting diodes are coupled to a plurality of segment lines and a plurality of common lines in a matrix structure. The organic light emitting diodes coupled to the same common lines are divided into a plurality of groups according to colors of the OLED panel. Driving currents are provided to the organic light emitting diodes of the groups according to a plurality of pulse width modulation (PWM) manners. The PWM manners generate waveforms having pulse width corresponding to grayscale in a period, wherein each PWM manner corresponds to different colors of the OLED panel.