A LED lamp holder includes a lamp cover and a heat-dissipating device provided in the lamp cover. An accommodating inlet is provided on the lamp cover. A LED unit is provided below the lamp cover. A cover plate covers the accommodating inlet. The heat-dissipating device includes a heat-absorbing plate, a heat-dissipating plate and a heat pipe connected between the heat-absorbing plate and the heat-dissipating plate. The heat-absorbing plate is brought into contact with the LED unit, while the heat-dissipating plate is brought into contact with the cover plate. The cover plate is penetrated by a plurality of screw elements. Each of the screw elements is screwed to the heat-absorbing plate. The length of each screw element exactly makes the heat-absorbing plate to abut and contact the LED unit.