An impedance matching circuit is disclosed. The impedance matching circuit adapted to an antenna includes a signal feed-in line, a phase delay line and a synthesized transmission line. The signal feed-in line receives an input signal from a wireless transceiver circuit. The phase delay line is electrically coupled between the antenna and the signal feed-in line, and delivers the input signal from the wireless transceiver circuit to the antenna. A first terminal of the synthesized transmission is electrically coupled to the signal feed-in line and the phase delay line. A second terminal of the synthesized transmission is configured to be opened. Based on the antenna operates in a first transmission medium or a second transmission medium, the input signal is transmitted to the antenna through different patterns selectively.