A method and circuit for matching impedance, wherein, a peripheral impedance detection module detects the user telephone impedance and outputs information about the user telephone impedance; an analog switch handover module provides an impedance matching path between the user telephone impedance and an impedance matching module according to information about the user telephone impedance output by the peripheral impedance detection module; the impedance matching module provides a corresponding impedance to match the user telephone impedance through the impedance matching path provided by the analog switch handover module. The above-mentioned technical scheme realizes the impedance matching when communicating between a wireless access box and telephones with different impedance modes. The matching process is automatic and flexible and does not need the manual configuration, and the realization technology is simple and reliable, and the cost is low.