This application relates to an accessory device used for at least one first device. The accessory device includes: a transceiver unit, configured to: communicate with the at least one first device, and obtain device information of the at least one first device; and a control unit, configured to: write the device information of the at least one first device obtained by the transceiver unit into a near field communication storage medium; and when an NFC connection is established between the accessory device and a second device, control the transceiver unit to send the device information of the first device to the second device. In this application, the NFC storage medium in the accessory device is readable and writable. The accessory device communicates with different first devices according to user requirements, and obtains device information of the different first devices.