An LED assembly for an LED lamp includes a replaceable bracket and a plurality of LED units mounted on the bracket. The bracket includes a frame and a plurality of mutually crossed beams interconnected in the frame to define a plurality of square openings. Each LED unit includes a printed circuit board, a heat sink secured below the printed circuit board and fixed on the bracket, and a plurality of LEDs mounted on the printed circuit board to be exposed in the openings in the bracket. The bracket can have different configuration so that light beams generated by the LEDs are parallel to each other, in a convergent manner or in a divergent manner.