The present invention discloses an antenna tuning system and method thereof. The method comprises the following steps: choosing a parasitic antenna that combined with a main antenna, the strongest received signal strength indicator of a target station is detected; controlling the selected parasitic antenna that combined with a main antenna, to generate a scattering resonance through turning on or off a switch unit; and controlling a diffraction radiation pattern between the main antenna and the selected parasitic antenna through adjusting a load of a designed circuit.