Switching power supply output frequency regulating circuit

The invention discloses a switching power supply output frequency regulating circuit which comprises a detection module and a regulation module. A first input end of the detection module receives a feedback voltage; a second input end of the detection module receives a sampling control pulse signal; a third input end of the detection module receives a first reference voltage, and an output end of the detection module outputs an error detection amplification signal; a first input end of the regulation module receives the error detection amplification signal, a second input end of the regulation module receives a second reference voltage, a third input end of the regulation module receives a frequency control voltage, and an output end of the regulation module outputs a frequency regulation voltage; and when a voltage of the error detection amplification signal is higher than the second reference voltage, the frequency regulation voltage is lower than the frequency control voltage, and when the voltage of the error detection amplification signal is not higher than the second reference voltage, the frequency regulation voltage is equal to the frequency control voltage. According to the switching power supply output frequency regulating circuit disclosed by the invention, a switching frequency of a power switch is improved, and effects of eliminating audio noise, improving system efficiency and promoting a system response speed are achieved.