An LED lamp includes a heat sink having a base and a plurality of LED module assemblies mounted on a top surface of the base of the heat sink. Each of the LED module assemblies includes a fixing bracket secured to the top surface of the base, an LED module mounted on a top surface of the fixing bracket and two heat pipes engaging with the fixing bracket and the heat sink. The fixing bracket includes a bottom plate attached on the top surface of the base, a top plate on which the LED module is attached and a connecting plate interconnecting the bottom plate with the top plate. The heat pipes thermally connect the bottom plate and the heat sink with the top plate.