A matching network system combined with a circulator, and a method thereof are provided. In the matching network system and method, a reflection coefficient per frequency, required to cancel a signal leaked (a leakage signal) from a port combined with an antenna (an antenna port) is calculated, an impedance value is calculated from the calculated reflection coefficient, and any antenna is matched to a matching network by using a matching network circuit for changing an impedance value of the antenna to the calculated impedance value. Therefore, cancellation of the leakage signal is controlled. In this manner, the isolation performance of the circulator in a plurality of frequencies can be increased.