This specification discloses a adaptive dual-slope frequency controller for adjusting power conversion of a power supply. The converter can adjust its operating frequency according to the status of a load device. A feedback voltage, representing the load status, is used to control two pairs of charging/discharging currents of a storage capacitor in the present controller, thereby controlling the period of the voltage waveform at the capacitor. This controller can especially lower the frequency of the gate pulse of power supply to improve the overall efficiency at light load and no load.