A control circuit of a power converter includes: an input signal detection circuit, configured to operably detect a magnitude of an input signal to generate a detection signal; a clock generation circuit, configured to operably generate a clock signal; an error detection circuit, configured to operably generate an error signal according to a reference signal and a feedback signal; a control signal generation circuit, coupled with the clock generation circuit and the error detection circuit, configured to operably control a switching frequency of a power switch according to the clock signal and the error signal; and a reverse adjusting circuit, coupled with the input signal detection circuit, configured to operably adjust the clock generation circuit or the control signal generation circuit according to the detection signal to configure the switching frequency of the power switch to be inversely proportional to the magnitude of the input signal.