Embodiments of the present invention disclose a server, and relate to the field of computer communications, so that maintainability of a server is improved, a heat dissipation function of the server is ensured, and heat dissipation reliability of the server is improved through online replacement of a heat dissipation fan and a server mainboard. A server includes: a chassis, a backplane with a ventilation opening, a rear board, a first air ducting apparatus, and at least one fan module, where the backplane is located in the middle of the chassis, and the rear board is connected to a rear side of the backplane in a pluggable manner; the fan module is disposed side by side with the rear board along a horizontal direction, and is connected to the rear side of the backplane in a pluggable manner.