The invention relates to a method and system for separating safety control and an anti-demounting function from an OBU main body. The system comprises the vehicle-mounted unit OBU main body, wireless vehicle identification tags and road side units (RSUs). Each wireless vehicle identification tag comprises a safety chip, a coupled antenna and loaded paper media, the vehicle-mounted unit OBU main body is connected with the wireless vehicle identification tags in a wireless communication mode, and the RSUs are connected with the vehicle-mounted unit OBU main body in a wireless communication mode. Through the adoption of the method and system for separating the safety control and the anti-demounting function from the OBU main body, the safety control and the anti-demounting function of the OBU are made to be separated from the OBU main body, a user is made to replace OBU products freely according to needs, the internal circuit of the OBU is made not to be in a power-on detecting state all the time, and the service time of the internal batteries of the OBU can be prolonged.