The application of LCD has been very common. One important inspection item for LCD manufacturers is screen flicker, and its optimization has become a crucial task. An automated inspection system that aims to achieve such a goal is presented. It uses photodetector to detect the degree of LCD screen flicker and converts the detected result to digital signal by sampling circuit, acquires the degree of flickering by signal analysis, and applies signal control method to adjust LCD's VCOM voltage which optimize LCD flickering automatically to improve measurement efficiency and meet the product requirements. This translates into an improvement in efficiency by 90%, and the accuracy is also improved.