An energy-saving illumination system includes a piezoelectric floor, a revolving door, an accumulator, a light source, and an electrical power sensing device. The piezoelectric floor contains piezoelectric material therein. The revolving door comprises a power generating device. The accumulator is electrically connected to the piezoelectric floor and the power generating device. The light source is electrically connected with the accumulator. The electrical power sensing device is configured to detect the quantity of electric charge in the accumulator; the power generating device of the revolving door charges the accumulator according to the detected result obtained from the electrical power sensing device in respect to the accumulator.