The present application discloses a control circuit of a switching power converter, wherein the switching power converter comprises a power switch, and is configured to convert an input voltage into an output voltage, the control circuit comprises: a first time generating circuit configured to generate a first time signal; a phase lock circuit configured to generate a second time signal; and a switching signal generating circuit configured to generate a switching signal to control the ON and OFF switching of the power switch. The phase lock circuit generates the second time signal in accordance with the frequency difference between the switching signal and a reference clock signal, so as to get the frequency of the switching signal to be substantially equal to the frequency of the reference clock signal.