What is concerned is a power supply having a power status indicator, in which the power status indicator is powered by a constant voltage source, such as a constant voltage provided by an auxiliary power supply or a reference voltage provided for the internal control circuitry. Or otherwise, the power status indicator is connected in series with a feedback circuit or a protection circuit of the power supply, and the current-limiting resistor thereof is eliminated. In this way, the power consumption of the power supply under the standby mode is reduced, and the energy utilization of the power supply is enhanced.