The present invention provides a power converter, and a control circuit and a standby power saving method thereof. The power converter provides an output voltage from an output terminal through an enable switch circuit to a power receiver. A detection signal shows whether a voltage at a signal transmission pin of the power converter is in a predetermined range, if not, the enable switch circuit is turned OFF. The power converter adjusts a feedback signal according to the detection signal or according to the detection signal and the output voltage, so as to adjust the output voltage to be lower than a normal operation level in a normal operation mode, to save power in a standby mode.