The invention provides an automatic impedance matching method and a matching system of the electrodeless lamp power supply, wherein the matching system comprises a first matching network, a second matching network, a high frequency cable, a first sensor, a second sensor and a controller. The controller judges whether the equivalent impedance of the electrodeless lamp is an effective impedance according to the detection value of the first sensor, if the equivalent impedance is judged to be an invalid impedance, the impedance value of the variable impedance component in the first matching network is calculated according to the model between the first matching network output impedance as well as the electrodeless lamp equivalent impedance and the first matching network variable impedance, and the variable impedance components in the first matching network and the second matching network are adjusted according to the model between the second matching network output impedance as well as the high frequency network characteristic impedance and the second matching network variable impedance. The invention realizes impedance matching between the electrodeless lamp power supply and the lampwhen high frequency cable is connected, thus ensuring normal operation of the lamp, saving matching resources and reducing matching energy consumption simultaneously.