An exemplary server system includes a server cabinet, a number of racks received in the server cabinet, a number of servers mounted in the racks, and a heat dissipation device. The server cabinet includes a top plate, a bottom plate, and two end plates between the top and bottom plates. Each end plate defines an opening at a top end thereof and a plurality of apertures at a bottom end thereof. The servers are stacked between the end plates of the server cabinet with a channel defined therebetween. The heat dissipation device includes an intake fan arranged under the racks with air intakes thereof facing the apertures and air outlets thereof facing the channel, and two drawing fans respectively arranged at the openings of the two end plates for exhausting heated air of the server cabinet to the exterior.