Abstract: After 6th-instar larva Helicoverpa armigera was fed on non-steroidal ecdysone agonist RH-2485,proteins and esterases in some tissues of them were examined,and the slices of body wall were observed with optical microscopes.SDS-PAGE resulted in that the expression of a major protein decreased in fat body and body wall of the group fed for 24 h and 48 h;Native-PAGE indicated that the expression of new esterases appeared in hemolymph and midgut of the group fed for 48 h.The body wall structure of the larva fed for 24 h showed some features of ecdysis (mesocuticle and endocuticle became vacuoles,and epicuticle and exocuticle separated from epidermis),and abnormal ecdysis (epidermis became obviously thinner than normal one).These results enhanced our knowledge of the mechanism of RH-2485 killing Helicoverpa armigera.