An illumination system and an operation method thereof are provided. The illumination system includes a first controller and a first lighting device. The first controller is capable of emitting a wireless control signal. The first lighting device is capable of receiving the wireless control signal, adjusting a light emitting state thereof according to the wireless control signal, and accordingly emitting a wireless feedback signal. When the first controller does not receive the wireless feedback signal within a predetermined time or receives a wrong wireless feedback signal after the first controller emitted the wireless control signal to the first lighting device, the first controller emits the wireless control signal again.