A dual mode charge control method includes steps of: detecting an input voltage of the resonance tank, a resonance current of the resonance tank, an output current of the load, and an output voltage of the load; performing a single-band charge control when determining a light-load condition or a no-load condition of the load according to the output current; compensating the output voltage to generate an upper threshold voltage in the single-band charge control, and acquiring a resonance voltage by calculating the resonance current by a resettable integrator; comparing the resonance voltage and the upper threshold voltage to generate a first control signal; generating a second control signal complementary to the first control signal by a pulse-width modulation duplicator; providing the first control signal and the second control signal to respectively control a first power switch and a second power switch of the resonance circuit.