Abstract: A flickering mode control system, for operating a high intensity discharge lamp at a flickering mode, comprises an output power controllable transformer and a flickering control unit. The flickering control unit outputs a power modulation signal to a switch the output power controllable transformer for determining a power of a direct current signal output from the output power controllable transformer. In a relatively dim state of the flickering mode, the high intensity discharge lamp has a low enough illumination, resulting in that it looks like the high intensity discharge lamp is completely extinguished. Actually, the high intensity discharge lamp still remains illuminated even in the relatively dim state of the flickering mode. Therefore, the flickering mode is realized without the use of a hot restike ignitor, thereby increasing a lifetime of the high intensity discharge lamp and its operation safety.