A wireless communication system is disclosed. The present invention mainly includes a transceiver, a first filter unit, a second filter unit, and a first amplifying unit, wherein the first filter unit is a harmonic oscillation circuit having an inductive component and a capacitive component serially coupled to each other, and the harmonic oscillation circuit as well as the circuit of the second filter unit efficiently filter out a local oscillation frequency signal and intermediate frequency signal traveling along with a radio frequency signal, thereby preventing neighboring communication systems from electro-magnetic interference due to radiation of the local oscillation frequency signal and intermediate frequency signal into air via an antenna after being amplified by the first amplifying unit.