A liquid cooling apparatus has a chassis, a cover mounted on the chassis, and a dividing structure disposed in an inner chamber defined between the chassis and the cover. The dividing structure divides the inner chamber into a liquid inlet compartment and a liquid outlet compartment. The liquid inlet compartment communicates with the liquid outlet compartment via the recess. The liquid cooling apparatus can be installed on a first panel with the boss of the chassis mounted through a through hole of the first panel and thermally attached to a heat source on a second panel. A working fluid that flows into the liquid inlet compartment is forced to flow into the recess before flowing to the liquid outlet compartment by the dividing structure. Accordingly, heat generated by the heat source can be effectively dissipated.