An electric appliance with constant power supplied-bus includes a power supply and a motherboard. A power transformation system of the power supply defines a main power system, which is electrically connected to an external power source for converting thereof as the electric appliance is under operation, and a standby power system, which has a constant electrical connection with the external power source for converting thereof into DC power, wherein the DC power outputted by the standby power system is used to drive a power on/off unit, which is used for outputting electric appliance-operating/appliance-shutdown signals. A bus is installed on the surface of the electric appliance and has a power transmission terminal and a data transmission terminal simultaneously, wherein the data transmission terminal is electrically connected with a data transmission port of the motherboard, and the power transmission terminal is electrically connected to the standby power system.