A heat exchanger of a sealed equipment cabinet includes a chassis, a heat-exchange module, a first fan and a second fan. The chassis includes a bottom plate having a plurality of first perforations. The heat-exchange module is disposed on the bottom plate, and defines first and second air flow channels at first and second sides of the bottom plate, respectively. The first fan is disposed on the first side of the bottom plate. The second fan is disposed on the second side of the bottom plate.