A driving device, a light emitting diode (LED) driving device and a method thereof are provided. The driving device includes a driving unit and a plurality of selection units. The driving unit produces a driving signal to drive a light emitting diode. The selection units are coupled to the driving unit and respectively correspond to a current value. The driving unit selects one of the selection units according a first pulse width modulation (PWM) signal. The current value corresponding to the selected selection unit is taken as the current value of the driving signal. The driving unit generates a duty cycle of a second PWM signal according to the duty cycle of the first PWM signal to serve as a duty cycle of the driving signal. In this way, power consumption of the LED is reduced.