An exemplary server system includes a server cabinet, two rows of racks arranged in the server cabinet, a number of servers mounted in the racks and a heat dissipating device. The server cabinet includes two side plates parallel to each other. The servers of each row are evenly distributed between the side plates. A channel is defined between the two rows of racks. The heat dissipating device includes an air conditioner arranged over the racks for generating cooling air and an air guiding mechanism. The air conditioner defines a number of apertures facing the passage. The guiding mechanism includes a number of tubes received in the passage and respectively coupled to the apertures of the air conditioner. Each of the tubes defines a number of air outlets for exhausting the cooling air towards the servers.