A modulation control method and system for a resonance circuit that generally relate to electrical communication technique. In the system, a controlling chip of the resonance circuit is connected to associated controlling means providing voltage matching and resistance control. The controlling means provides controlling parameters to the chip in accordance with input voltage. The controlling chip modulates the resonance circuit accordingly. A phase-shifting pulse width modulation controlling chip or a pulse width modulation controlling chip is connected to a voltage matching module and a resistance controlling module, wherein the voltage matching module matches the voltage ranges and the resistance controlling module adjusts the equivalent resistance of RT terminal to the external as the voltage of loop circuit changes accordingly. In the method, a controlling chip is used to realize a controlling mode of frequency modulation, pulse width modulation, and combination thereof with respect to the resonance circuit through the voltage matching module and the resistance controlling module. The present invention is advantageous in low cost and high efficiency.