An LED lamp assembly includes a lamp supporter and an LED lamp supported by the lamp supporter. The LED lamp includes a lamp cover defining a first opening, a reflector received in the lamp cover and defining a second opening, a heat sink secured to a top of the lamp cover and a plurality of LED modules attached on the heat sink. The heat sink has a plurality of heat-conducting faces formed on a periphery thereof and the LED modules are attached on the heat-conducting faces to generate a wide illumination. The heat sink defines a through hole. Heat generated by the LED modules is absorbed by the heat-conducting faces and directly dissipated to an exterior through the first opening of the lamp cover. The first and second openings and the through hole of the heat sink are communicated with each other.