The invention belongs to the technical field of vehicle-mounted navigation systems and particularly relates to an updating device and an updating method of a Beidou vehicle-mounted navigation system. The updating device comprises a Beidou navigation terminal, a mobile phone terminal and a background service terminal, wherein the Beidou navigation terminal is used for sending current version information of the Beidou navigation system to the mobile phone terminal, the mobile phone terminal is used for obtaining position information of to-be-updated data in the Beidou navigation terminal and sending the position information to the background service terminal by dialing a phone of the background service terminal, the background service terminal sends the position information to the Beidou navigation terminal and is used for encoding last updated data to obtain data in an audio format and sending the data in the audio format to the mobile phone terminal, and the mobile phone terminal sends the data in the audio format to the Beidou navigation terminal. The vehicle-mounted navigation system can be rapidly, efficiently and accurately updated in real time.