An LED lamp includes a heat sink, a plurality of vapor chambers mounted on the heat sink and an LED module mounted on the vapor chambers. The heat sink includes a base, a plurality of fins extending from a first surface of the base and a triangular ridge formed on a second surface opposite to the first surface of the base. The vapor chambers are mounted on the ridge of the base. The LEDs over two slopes of the ridge are oriented slantwise outwardly, thereby increasing an irradiation angle and area of the LED lamp.