Abstract: For understanding the communication between stem pests and preventing their harms, the ultrastructure of stridulatory organs of three long-horned beetles including Leptura arcuata Panzer, Anoplophora glabripennis Motschulsky and Massicus raddei Blessig were observed by scanning electron microscope, and the stridulation mechanism of these pests were analyzed also. The results showed that ultrastructure of stridulatory organ of three longhorned beetles were different among three species. It was discovered that there were neat bristles indwelling on the margin of pronotum of the three tested long-horned beetles,and a lateral sulcus in the sound plate of A.glabripennis Motschulsky.