The invention provides a heat exchanger for a communication cabinet. The heat exchanger comprises a shell and a heat exchange device, wherein the a first space and a second space, which are separated from each other, are formed in the shell; the first space is communicated with the communication cabinet, and the second space is communicated with the outside world; the heat exchange device comprises a first heat exchange part positioned in the first space and a second heat exchange part positioned in the second space; communicated heat transfer media are arranged on the first heat exchange part and the second heat exchange part, and the heat transfer medium on the first heat exchange part absorbs the heat of the first space; the heat transfer media circularly flow between the first heat exchange part and the second heat exchange part, so that cooling is realized. By adopting the technical scheme, the heat exchanger does not need to consume external mechanical power and electrical power in the working process and is low in energy consumption, and the shell is simple in manufacture process, low in manufacture cost, and convenient to mount, dismount and use.