A vehicle monitoring system, comprises: at least a sensor; a head unit; at least a smart unit; wherein the sensor is capable of detecting vehicle status, generating a corresponding signal and then sending the generated signal to the head unit; the head unit is capable of receiving and analyzing the generated signal, and generating an analysis result, and they informing whether the vehicle status is abnormal by outputting a warning in the vehicle or sending the analysis result to the smart unit; the smart unit is authorized by the head unit and capable of displaying the analysis result.