The invention belongs to the field of automobile safety control, and particularly relates to the field of control and detection for the air pressure of an automobile tire. A monitoring system for the air pressure of the automobile tire comprises a controller, a low-frequency trigger and a tire-pressure sensor, wherein the low-frequency trigger and the tire-pressure sensor are connected with the controller; an LIN bus is adopted for transmitting signals between the controller and the low-frequency trigger; a wireless mode is adopted for transmitting the signals between the low-frequency trigger and the tire-pressure sensor; a wireless mode is adopted for transmitting the signals between the tire-pressure sensor and the controller. The monitoring system has the advantages that a driver can know information such as air pressure and temperature of the vehicle tires in real time, and when the forewarning states of flat tires such as air deficiency, air leakage or overhigh tire temperature occur, the tires emit light or sound to give an alarm for reminding, so that the driver can adopt preventive measures such as speed reduction, stoppage and air supplement actively to prevent accidents from occuring.