Abstract: A battery car anti-theft device, which is mainly characterized in utilizing an electronic control circuit to control the external power supply state of a battery, and when set in the anti-theft state, if it is detected that the supply current is greater than a preset value, then the entire external power supply of the battery is immediately cut off, thus, there is no power supply to start the engine to enable the car thief to drive the vehicle away, thereby achieving the objective of preventing the vehicle from being stolen.