A two-level LED security light within it has a light-emitting unit including an LED load which may be turned on or turned off by a loading and power control unit activated by a light sensing control unit and a motion sensing unit. When the motion sensing unit detects a motion signal, the light-emitting unit is switched to a high level illumination for a predetermined time length adjustable by a time setting unit, and then the loading and power control unit manages to turn off the light-emitting unit thru a soft off process. The LED load is configured with a plurality of LEDs accommodating to the power supply unit wherein a voltage V across each LED is confined in a range Vth