Automatic lighting control systems which is controlled by motorial control boards and executed by harmonizing alterable diaphragm with electronic shutter in High-Speed TV Measure Instrument is incroduced. In this way,it would widen system's dynamic range of adjusting light. Adopting get feedback signal conbined average gray with peak gray,adaptability of automatic lighting control systems can be effectively solved in diversified background. Putting forward arithmetic base on Quadratic Function to calculate feedback quantity,Convergent Velocity during lighting can be improved and smaller overflow of the system can be insured.