An electronic device and a method for recognizing output power of a power supply thereof are provided. The electronic device includes a host and a power supply. The power supply is coupled to the host, receives an input power and converts the input power to a supplied power. The power supply transmits the supplied power to the host, and loads a notification signal to the supplied power in at least a time period. The acknowledge signal is a periodic clock signal, and corresponds to the output power of the power supply. The power supply loads the acknowledge signal to the supplied power in one or more time periods, and transmits the acknowledge signal to the corresponding host. The host can get the output power of the power supply via the acknowledge signal, which can improve efficiency and security of the supplied power.