A light emitting diode (LED) driving circuit is provided. The LED driving circuit includes a voltage adjusting unit, a switch unit, and a control unit. The control unit is coupled to the voltage adjusting unit and the switch unit. The voltage adjusting unit outputs a driving voltage to a first end of each of a plurality of load units. The switch unit is coupled to a second end of each of the load units. When one LED string in the load units is coupled to a current source, the voltage adjusting unit adjusts the voltage level of the driving voltage so that the voltage level of the driving voltage of the driving voltage corresponds to the driven LED string. Thereby, a driving problem caused by the variation in electrical characteristics of the LEDs is alleviated.