A liquid-cooled heat sink includes a heat absorption module having a liquid storage container with one heat conductive side, a liquid inlet and a liquid; a liquid transport module including one inlet tube having a first end connected spatially with the liquid inlet of the storage container and a second end connected spatially with a pump unit, and an outlet tube having a first end connected spatially with the liquid outlet of the storage container and a second end connected spatially with a storage chamber; and a heat exchange module including a fin assembly, one connection passage extending through the fin assembly and one fan unit disposed on the fin assembly, which has two opposite ends respectively connected to the pump unit and the storage chamber, the connection passage having two opposite ends respectively connected to the pump unit and the liquid storage chamber.