An LED lamp includes a hollow lamp housing, a front optical part, a rear electrical part, and a middle heat dissipation part. The heat dissipation part includes a heat sink, a mounting seat in front of the heat sink, and a heat conducting member connecting the mounting seat with the heat sink. The lamp housing defines a plurality of air exchanging holes corresponding to the fins. The mounting seat includes a small top surface, an opposite large bottom surface, and a plurality of sloping heat absorbing surfaces between the top surface and the bottom surface. The optical part includes a plurality of light sources arranged on the heat absorbing surfaces, a light reflector located between the heat sink and the mounting seat and surrounding the heat conducting member, an optical lens located in front of the light reflector and the mounting seat.