An expansion module includes a housing, at least one first wedging device, a connecting device, and a module socket. At one side of the housing, there is at least one plugging pin. The first wedging device is located in the housing. The first wedging device corresponds to the plugging pin. The connecting device has a first connecting portion and a second connecting portion. The first connecting portion is electrically connected with the second connecting portion, and the first connecting portion and the second connecting portion are located at the two opposite sides of the housing. The module socket is located in the housing. The module socket is electrically connected with the connecting device. The user can easily uninstalled or installed the expansion module, the time is reduced, and it prevents the plugging pins of the module card from being damaged due to external force.