The present invention discloses an Ethernet base, a network system, and a data forwarding method. The Ethernet base receives service data which is in a USB format and sent by a 3G router, and after converting the service data in the USB format into service data in an Ethernet format, sends the service data in the Ethernet format to a fixed network router. The Ethernet base further performs software configuration on its USB unit, so as to enable the USB unit to fulfill a hardware time sequence function of a USB host device. According to embodiments of the present invention, network traffic of the 3G router can be switched to the fixed network router without modifying basic architecture of the 3G router; and a USB interface of the Ethernet base supports charging the 3G router simultaneously in a process of data transmission.