A lighting system includes: a power supply circuit, an AC-DC converter circuit and a wireless communication module. The wireless communication module receives an external command from a wireless communication device and generates an adjustment command according to the received external command. The adjustment command includes a luminance adjustment command and a driving power control command. The power supply circuit includes a power stage and a conversion controller circuit. The conversion controller circuit supplies a adjustable output voltage to the wireless communication module, to power the wireless communication module. The conversion controller circuit controls the power stage according to the luminance adjustment command, to adjust an output current of an output power, thereby adjusting the luminance of a light emission device. And, the conversion controller circuit controls the adjustable output voltage according to the driving power control command, to regulate the adjustable output voltage to a high voltage level or a low voltage level.