Abstract: To study the mechanism of energy reflection and transmission of ultrasonic in the adhesive structure,under the assumption of perfect connection,the ultrasonic wave interaction with the interfaces of plate-like adhesive structure was studied when the longitudinal waves were incident with different angles. The effects of the incident angles,frequency-thickness product on the reflection and transmission characteristics of ultrasonic energy were analyzed. The numerical results show that when the longitudinal waves are vertically incident, the conversions of wave mode do not occur, with the increment of frequency-thickness product,the reflection and transmission coefficient curves of energy of longitudinal waves obviously produce periodical resonance. When the longitudinal waves are obliquely incident,the conversions of wave mode will happen,as the product of frequency-thickness increases,the reflection and transmission coefficients of energy of longitudinal and transverse waves do not have periodical resonance. For the case of the incident angles less than 90°,the displacement potential reflection coefficients of longitudinal waves are always bigger than the energy reflection coefficients; however,the reflection coefficient curves of displacement potential and energy for transverse waves occur cross with increasing angles. The results provide a theoretical basis for the experimental detection of adhesive structure by ultrasound.