An LED light source includes an LED module and a light-guiding module fixed on the LED module. The LED module includes a printed circuit board and a plurality of LEDs. The light-guiding module includes a frame placed on the LED module and a plurality of light guiding units engaging with the frame. The frame defines an opening in a lower portion thereof to receive the LEDs of the LED module therein and a recess in an upper portion thereof and in communication with the opening. Each of the light guiding units has a base with two flanges respectively fittingly received in two cutouts of the recess of the frame so that the light guiding unit is movable along the recess until it faces a corresponding LED.