An LED lamp includes a heat sink, a plurality of LED modules mounted on the heat sink and a plurality of light-guiding modules respectively fixed on the LED modules. Each light-guiding module comprises a frame having a bottom panel placed on the LED module and two side panels extending upwardly from two opposite edges of the bottom panel and a plurality of guiding units each having two engaging flanges extending outwardly from two opposite lateral sides thereof. Each guiding unit receives an LED of a corresponding LED module therein. The two side panels respectively define two runners in inner sides thereof. The two engaging flanges of each guiding unit are respectively received in the two runners of the frame and movable therealong to adjust a position of the guiding unit in the frame.