The inveniton provides a driving circuit and its method of light emitting diode. The driving circuit comprises a control unit, a current control unit, a pulse width modulation control unit and a current driving unit is described. The control unit provides a first control signal and a second control signal. The current control unit is connected to the control unit, and converts a reference current into a plurality of current setting signals based on a data signal and the first control signal. The pulse width modulation control unit is connected to the control unit and outputs a pulse signal based on the data signal and the second control signal. The current driving unit is connected to the pulse width modulation control unit and drives the light emitting diode based on a driving current, wherein the control unit generates a continuous conduction time in a predetermined operation period based on the pulse signal and the current setting signals.