Abstract In the field of non-destructive testing (NDT), The detection of bonding defects between ultra-thin metal and silica gel is a difficult problem. In this study, In this study, ultrasonic resonance method was used to evaluate the bonding strength of ultra-thin metal to silica gel bonding structure. The composite parts of ultra-thin nickel sheet and silicon sheet with three different bonding states were studied. The bonding state of nickel sheet and silica gel is different, and the absorption of ultrasound is different. Using the resonance generated by high-frequency ultrasound in ultra-thin nickel sheet, the acoustic attenuation of the combination of ultra-thin nickel sheet and silicon rubber sheet was analyzed by resonance signal, and the bonding state between ultra-thin nickel sheet and silicon rubber sheet was characterized by bonding coefficient. Through experimental comparison, the results showed that the attenuation of ultrasonic signal in the nickel sheet and silicon film with different adhesive states characterize the adhesive state of ultra-thin nickel sheet and silicon film by the bonding coefficient, the bonding coefficient of good parts, weak adhesive parts and debonded parts is reduced successively. By setting an appropriate determination threshold value, the bonding state between the ultra-thin nickel sheet and the silicon film can be accurately determined according to the bonding coefficient obtained by detection.