A buck-boost switching regulator includes: a power switch circuit including an input switch unit and an output switch unit; a bypass control circuit configured to operably generate a bypass control signal according to a conversion voltage difference between an input voltage of an input power and an output voltage of an output power and according to whether an inductor current flowing through an inductor reaches an output current of the output power; and a bypass switch circuit, wherein when the conversion voltage difference is below a reference voltage and when the inductor current flowing through the inductor reaches the output current, the bypass control signal controls the bypass switch circuit to electrically connect the input power with the output power, so that the buck-boost switching regulator operates in a bypass mode.