In order to improve the detection efficiency of debonding defects in bonded structures and achieve rapid and automatic detection in large areas，air-coupled ultrasonic lamb wave detection technology is proposed to detect and study the defects of steel/resin/rubber bonded structures based on the leaky Lamb wave detection principle.The two-dimensional Fourier transform was used to analyze the Lamb wave modes，and the sensitivity of different modes of Lamb waves to debonding defects was analyzed. The defects of different sizes were quantitatively studied by the air-coupled detection system.Finally，the probability damage imaging algorithm was used to image the defects. The amplitude of the lamb wave increases with the size of the debonding defect.Different Lamb wave modes have different detection sensitivities，and the modal with high detection sensitivity has greater off-plane displacement.Using 800 kHz S₀ mode detection sensitivity is higher than A₀ mode，the Lamb wave imaging algorithm can quickly and accurately locate the debonding area.Air-coupled ultrasonic Lamb wave technology can quickly and effectively detect SRM debonding defects，improve detection efficiency，and provide beneficial exploration for the practical application of non-contact ultrasound.