A control system includes a detection circuit, a control circuit, and a dummy load system. The detection circuit is operable to detect a voltage level change of a direct-current voltage and output an activating signal when detecting the voltage level change of the DC voltage. The control circuit is operable to receive the activating signal. The dummy load system is electrically connected to the control circuit, and the control circuit controls the dummy load system by generating a turn-on signal in response to receiving the activating signal. A dimmer system and a control method thereof are further disclosed herein.