The present application discloses a car rental system, which comprises an vehicle-mounted equipment, an identity nameplate and a cloud control platform. The vehicle-mounted equipment comprises a vehicle-mounted communication device and a vehicle-mounted monitoring device. The identity nameplate is provided with an RFID tag. The vehicle-mounted monitoring device comprises an RFID card reader, a vehicle-mounted battery detector, an alarm controller and a buzzer alarm. The vehicle-mounted communication device reads the detection signal of the vehicle-mounted monitoring device and uploads the detection signal to the cloud control platform through the network, and receives the feedback control signal of the cloud control platform. The cloud control platform comprises an information registrationunit, a database unit, an identity authentication unit, an anti-theft alarm unit and an electric quantity alarm unit. The anti-theft alarm unit is used for sending an alarm signal. The electric quantity alarm unit is used for feeding back the electric quantity alarm signal. The alarm controller is connected with a buzzer alarm, and controls the buzzer alarm to output a low-power alarm signal whenthe electric power alarm signal is received. The application can monitor the two taxis in real time, and has the performance of security and anti-theft.