An LED lamp includes a heat sink, a heat pipe and an LED. The heat sink includes a connecting core and fins mounted around the connecting core. Each of the fins includes a plate-shaped main body and a flange extending perpendicularly from a periphery side of the main body. The flanges of the fins cooperatively form an annular planar top surface of the heat sink. The heat pipe includes a condensing section, an evaporating section parallel to and higher than the condensing section and an adiabatic section connected between the condensing section and the evaporating section. The condensing section is fixed to and thermally connects with the top surface of the heat sink. The LED is directly mounted on the evaporating section with a light emitting surface thereof facing outwardly.