A power management interface is provided and includes a switch, a transmitting circuit, and a receiving circuit. The switch is coupled to an AC power line for controlling a power line signal to a load. The transmitting circuit generates a switching signal to control the switch and achieve a phase modulation to the power line signal in response to a transmitting-data. The receiving circuit is coupled to receive the power line signal for detecting a phase of the power line signal and generating a receiving-data to control power of the load. The receiving-data is generated in accordance with the phase detection of the power line signal and correlated to the transmitting-data.