It will impact the overall yield and quality of wheat if the malnutrition in the wheat growing season is not timely found. Thus, it is necessary to carry out timely nutrition detection of the wheat population in the field. Based on the techniques of Java web development and image processing, this paper constructs the estimation model of the field wheat population condition, designs and implements the automatic nutrition detection and analysis system based on field wheat population images. By using the received images of crop growth group, the system detects the nutrition condition of wheat population cultivated in the field quickly, and gives assisted fertilization decision to farmers for reducing the effect of wheat malnutrition on the yield and quality of wheat.