Abstract: In this study, using image processing technology and genetic neural network technology, a three-layer feed forward neural network was established, which can identify corn from background correctly. The external color feature of corn leaves was extracted from the hue histograms. The measured color value of corn leaves was calculated. The experiment showed that corn could be recognized correctly by using this automated measurement system of corn leaf color value, the judging accuracy could attain 91.6%, and corn leaf color value could also be calculated correctly. This research work may provide theoretical foundation for precisely fertilizer spread in corn field.