A LED driving apparatus and an operating method thereof are disclosed. The LED driving apparatus includes a power, at least one LED string, a LED control unit, and an input voltage detection circuit. At least one LED string is coupled to the power and includes LEDs connected in series. The input voltage detection circuit is coupled to two ends of at least one LED of the LEDs respectively and used to judge whether an input voltage is lower than a LED conducting voltage. The input voltage detection circuit includes a charging capacitance to be charged when the at least one LED string is conducted. If the judged result of the input voltage detection circuit is yes, the input voltage detection circuit will control the charging capacitance having a charging voltage to discharge to the at least one LED string.