A wireless vehicle burglar-alarm system formed of an on-board main unit and a wireless communication is disclosed. The on-board main unit obtains the CGI (Cell Global Identity) of a wireless communication base station from its broadcast and stores the CGI in a memory, and sends a re-location signal to the on-board main unit when the storage CGI is changed during an alert mode of the on-board main unit, causing the on-board main unit to start the at least one alarm. The on-board main unit sends an alarm signal to an alarm and drives the wireless communication apparatus to send an alarm message to the car owner wirelessly upon detection of an abnormal condition of the car through a sensor.