The antennal surface structure of Cotesia chilonis was observed with the scanning electron microscope. Six types of sensilla were found on the antennae. They were sensillum placodea, sensillum trichodeum, sensillum chaetica, sensillum cylindric, sensillum campaniformia and sensillum basiconca. The shape of these sensilla and their distribution were described,the difference between male and female and their function was also discussed. none