Abstract: When green plants are sprayed with the aid of infrared detection, the untargeted soil and branches are covered meanwhile, which causes much waste of pesticides and pollution to environment. The infrared detection technology was discussed in this paper to detect the targets automatically, and identify the green targets using the color sensor, to achieve the aim of spraying the green plants exclusively. The results demonstrated that the equipment developed for automatic infrared detection succeeded in detecting automatically on green plants; the furthest detection range was 85~88cm, which was affected by leaves coverage rate and illumination; the larger leaves rate and the higher illumination of the leaf surfaces mean the further detection range. The detection range was large and stable under the condition of large leave coverage rate and high illumination, which provides a control strategy and method to precision pesticide application.