A switching control method capable of continuously providing power is utilized for a power supply system having a first power supply unit and a second power supply unit. The switching control method includes generating a first input signal and a second input signal; performing a logical operation process on the first input signal and the second input signal to generate a first control signal; delaying the second input signal for a delay time to generate a second control signal; controlling a coupling relationship between the first power supply unit and a load according to the first control signal; and controlling a coupling relationship between the second power supply unit and the load according to the second control signal.