A circuit for controlling standby power consumption is disclosed. The circuit includes a main power supply, a transformer, a first switch transistor, a load, a low frequency divider circuit, and a signal generation unit. The transformer connects to one end of the signal generation unit and an input end of the low frequency divider circuit. The signal generation unit transmits the level signals to the low frequency divider circuit according to the operating mode and obtains the power supply voltage of the transformer. The second frequency of the low level signals is greater than the first frequency of the high level signals. The source of the first switch transistor connects to a load to obtain the frequency of the output signals to be operating frequency so as to control the turn-on duration of the transformer. So the power supply voltage in the standby mode and the power consumption are reduced.