The present invention relates to a shared interface device for Power Over Ethernet (POE) and a wireless network module, comprises a motherboard and an interface device used for inserting a POE card or a wireless interface card. The motherboard includes an Ethernet connection interface, a signal processing unit, a logical conversion unit and an external power supply interface. When signals and power from an external network are transmitted via the Ethernet connection interface to the interface device, these signals and power will be further transmitted into the POE card for filtering to capture the power. Then, the captured power will be fed back to the interface device and transmitted via the logical conversion unit to the motherboard for use; when the logical conversion unit receives the power from the external power supply interface, the power is provided for the wireless interface card and the motherboard for use. Such shared design will effectively reduce complexity of circuit layout in the motherboard and lower costs for enterprises in developing a set of independent modules separately.