Abstract: A memory expansion device is provided and includes a shell and a memory expansion component. A contact surface, a heat dissipation surface and a heat conduction port are disposed on the shell. An accommodating cavity is arranged inside the shell. The heat conduction port penetrates through the contact surface and the heat dissipation surface and is separated from the accommodating cavity. The memory expansion component is arranged within the accommodating cavity. When the contact surface of the shell is in contact with an outer surface of the computer host, some heat dissipation holes on the bottom of the computer host correspondingly communicate with the heat conduction port on the shell, so that heat on the computer host can be dissipated to a side where the heat dissipation surface is located through the heat conduction port.