Aiming at the problem that the quality of bonding interface is difficult to detect and evaluate， an air-coupled ultrasonic guided wave method is proposed to detect bonding strength of the interface. Based on the propagation characteristics of ultrasonic guided waves in double layer medium and the theory of interface spring model， the dispersion equations for different bonding interfaces are derived. By numerically solving the dispersion equation， the dispersion curves of three interface qualities of rigid bond， slip bond and complete debonding are described， respectively. The analysis from dispersion curves shows that the phase velocity of guided wave is larger than that of sliding bond from A0 mode in a certain frequency range when the interface tends to be rigid bond. The phase velocity dispersion curves reveal dual symmetry and antisymmetric modes when the interface is complete debonding， which coincide with the dispersion curves of upper and lower layers. The phase velocities from the experiments are in good agreement with the numerically solving results. Under the condition of rigid bonding， the guided wave amplitude and acoustic energy are the minimum. The guided wave amplitude and acoustic energy are the maximum under the complete debonding. The results provide a theoretical basis for ultrasonic testing the quality of different bonding interfaces.