Abstract: To control plants disease with less pesticide, a spraying effect of the intelligent spraying robot for greenhouses was assessed. The information about disease location and state was obtained by machine vision sensors. Variable nozzles were driven by a three degrees of freedom cartesian coordinate manipulator, and pesticides were sprayed according to target position and lesion area. Boom location error and pesticide saving ratio were quantitative analyzed in the greenhouse experiment. The robot was tested on three disease levels. Compared with traditional spraying methods, this system saved over 60% of the herbicides. The robot can directly apply pesticide to cucumber individual lesion area and improve pesticides efficiency, reduce production costs and protect the environment.