An electronic device, a monitoring and feedback system on thoracoabdominal motion (TAM) and a method thereof are provided, where the method includes the following steps. TAM signals of a user in a natural state are measured. Next, the TAM signals are decomposed so as to extract main components thereof. Energy of the main component and the non-noise components of the abdominal motion signal are calculated to obtain the abdominal muscle contraction. Instantaneous phases of the main component of TAM signals are calculated to obtain the instantaneous coordination of TAM and the self-ability for adjusting TAM. A TAM mode of the user is evaluated in the natural state according to the abdominal muscle contraction, the instantaneous TAM coordination, and the self-ability for adjusting TAM. The user is further instructed to adjust the TAM mode to a suitable state according to a target environment mode.
