A switching controller for a parallel power supply is disclosed. The switching controller includes an input circuit coupled to an input terminal to receive an input signal for generating a phase-shift signal, a first integration circuit coupled to the input circuit to generate a first integration signal in response to a pulse width of the input signal, and a control circuit coupled to the first integration circuit to generate a switching signal for switching the power supply, the switching signal being enabled in response to the phase-shift signal, a pulse width of the switching signal being determined in accordance with the first integration signal.