An LED lamp includes a heat sink, a plurality of fin arrays mounted on the heat sink, and a plurality of LED modules mounted on the fin arrays. The heat sink includes a base and a plurality of heat dissipating fins extending from the base. The fin arrays are mounted on a top surface of the base of the heat sink. Each fin array consists of a plurality of fins interlocked together. Each fin array has a bottom mounting surface in contact with the top surface of the base and a top engaging surface defined at an acute angle with respect to the top surface of the base. The LED modules are mounted on the engaging surfaces of the fin arrays, respectively, via heat absorbing plates.