The present invention relates to an application of an insecticidal protein. A method for controlling a chilo sacchariphagus injurious insect comprises: the chilo sacchariphagus injurious insect at least contacts Cry2Ab protein. The present invention controls a chilo sacchariphagus injurious insect by generating Cry2Ab proteins capable of killing the chilo sacchariphagus in a plant body compared with an agricultural prevention and control method, a chemical prevention and control method and a physical prevention and control method used in the prior art, the present invention protects a whole plant in a whole growth period so as to prevent and control the damage of the chilo sacchariphagus injurious insect, has no pollution and no residue, is stable and thorough in effect and is simple, convenient and economical.
