The invention provides a vehicle-mounted device of an electric automobile. The device comprises a master control module, a CAN (controller area network) bus communication module, a 3G (third-generation) wireless communication module, a GPS (global positioning system) data receiving and processing module, and a user interaction module; the CAN bus communication module is in two-way connection with the master control module through an SPI (serial peripheral interface) bus, and the 3G wireless communication module, the GPS data receiving and processing module and the user interaction module are all in two-way connection with the master control module through a serial port. The vehicle-mounted device of the electric automobile has the functions of real-time monitoring of operation information of a vehicle and a battery, vehicle locating and navigating, and providing multimedia service, is suitable for intelligentized monitoring and management of the electric automobile industry, interaction of the electric automobile and a power grid, and remote diagnosis and emergency rescue of the vehicle, is fast in data collecting and processing, high in software platform development and operation efficiency, and friendly to a human-computer interface, and safe and reliable operation of the electric automobile can be guaranteed.