An exemplary low power consumption circuit includes a microprocessor, a power supply switch module and a main circuit module. The microprocessor is capable of outputting a power control signal and changing a pulse characteristic of the power control signal when the microprocessor switches from a first working mode to a second working mode. The power supply switch module is capable of outputting a power supply signal. The power supply switch module is electrically coupled to the microprocessor to receive the power control signal and thereby modulates a duty cycle of the power supply signal according to a change of the pulse characteristic of the power control signal. The main circuit module is electrically coupled to the power supply switch module to receive the power supply signal and operative with energy provided by the power supply signal. Moreover, a method for reducing power consumption is also provided.