The exposure time and signal gain can be used to adjust the light intensity for a conventional CCD camera,but both of them can not be configured best. It is also very difficult to maximize the effectiveness of their dimming, especially for the condition of the changed illumination intensity, the large dynamic range and the unclear picture.For the above-mentioned shortages, the histogram equalization certain improvements, the deployment of exposure time and signal gain were optimized through precise deployment of exposure time and optimization of signal gain coefficients. After the test, the screen effect has been significantly improved , the adjustment time is less than 40ms ,and the system is stable and reliable.