Provided is a method for controlling prodenia litura. The method comprises: allowing prodenia litura to be in contact with a Cry2Ab protein. The method specifically comprises: growing genetically modified plants by using polynucleotide coded with a Cry2Ab protein and allowing the prodenia litura to be in contact with the Cry2Ab protein by allowing the prodenia litura to eat genetically modified plants, wherein after the contact, the prodenia litura is restrained in growth and/or finally dies, so as to prevent the prodenia litura doing harm to plants.