A modularized water-cooling heat sink includes a cold discharge body, a water tank and a water pump. The water pump is connected with the water tank, and connected with the cold discharge body via an external cold head. The cold discharge body is provided with a first through hole in communication with outside, and the water pump is provided with a second through hole in communication with outside. The first through hole is located on the end of the cold discharge body away from the connection with the water pump. The water tank and the cold discharge body are detachably connected. The modularized water-cooling heat sink has such a modular structure design that it is assembled as simple as an integrated water-cooling heat sink, and that the heat dissipation effect thereof is as good as a split water-cooling heat sink.