An operating method of an electronic device is provided. The electronic device includes a display module and a detecting module. The operating method includes: detecting a first input signal by the detecting module; triggering an auxiliary displaying module according to the first input signal, and displaying the auxiliary displaying module on the display module; detecting a second input signal by the detecting module; determining whether the second input signal is in a sensing zone corresponding to the auxiliary displaying module; and displaying a drawing track along an edge of the auxiliary displaying module according to the second input signal when the second input signal is in the sensing zone.