A light emitting diode (LED) lamp comprises a lamp housing with a downward opening, a plurality of LED modules, a reflector and a lens covering the opening at the lower end of the lamp housing. The lamp housing is provided with a conical wall. The LED modules are attached to the inner side of the conical wall. The reflector is held in a lampshade and gradually shrinks and extends downwards from the top of the conical wall. The corrugated surfaces of the LED modules can improve the index of refraction of the lens so as to refract the illuminating light generated by the LED modules to farther places at smaller angles of emergence to expand the illuminated area of the LED lamp.