A USB hub device having functionality of self firmware updating is disclosed. The USB hub device is integrated in a host electronic system, and comprises an upstream port, a plurality of downstream ports and a hub module comprising a plurality of second USB controller units. On the other hand, the host electronic system has a second USB controller unit. After one electronic device is coupled to one downstream port, the first USB controller unit sends a detection signal for verifying whether the electronic device includes at least one firmware update data or not. In case of the electronic device being verified to have the firmware update data, the hub module transmit the firmware update data from the electronic device to a memory unit thereof, thereby completing a firmware update of the USB hub device.