A LED security light includes a power supply unit, a light sensing unit, a motion sensor unit, a loading and power control unit, an external control unit and a light-emitting unit. In responding respectively to signals outputted from the light sensing unit and the motion sensor unit, the LED security light is turned on at dusk for generating different level illuminations performed by the light emitting unit and turned off at dawn. The light emitting unit includes one or a plurality of LEDs. The external control unit is for setting illumination characteristics of the light emitting unit. The power supply unit comprises a solar power module as a first power source and a backup battery module as a second power source.
