A method for monitoring tire pressure variation of automobile tires and a system of implementing thereof, which measures and obtains rotation speeds of individual automobile tires as reference values, and compares these reference values with the current rotation speeds of individual automobile tires to inspect tire pressure variation of automobile tires and provide basis for determining fault tire locations. Compared with the conventional art, it has advantages to determine fault locations accurately, and deal with the problem of misreporting tire locations due to the influence in determining fault locations by the difference of specifications of tires, pressure or wearing degrees. In addition, the method and system can raise an alarm when two tires arranged axially or diagonally are in case of equal underpressure, and record data relating to the alarm signal and rotation speeds as the basis for distinguishing liabilities in case of accidents.