In the power source switching control system, a circuit breaker includes a controller and an on/off apparatus. The controller controls, based on a signal of a monitor, the on/off apparatus to adjust an on/off state of a power source connected to the circuit breaker, that is, adjust, from an on state to an off state based on a switch-off signal of the monitor, a working power source that is currently working, and adjust a backup power source from an off state to an on state based on a switch-on signal of the monitor, to implement a process of power source switching between the working power source and the backup power source.