A cup device for heating, stirring and foaming liquid foods comprises a cup, a cup lid, a handle, a stirrer, a motor drive disk, a plurality of magnets, an electric motor, a hot plate, a boil dry thermostat, a thermostat, a micro switch, a transformer, a controller, a heating base, a button, a button circuit board, connecting wires and bolts. The controller controls the work of the hot plate and the stirrer to input air into liquid foods, and therefore producing a lot of foams. The cup can be separated from the heating base, which enables it to be cleaned by a dishwasher. The stirrer turns along with the electric motor by magnetic attraction. The stirrer of removed cup will not naturally get off. The heating base only supplies power when the cup is put on it and it automatically cuts off power supply when the cup is removed.