Adhesive bonding is increasingly adopted in engineering structures, but poor bonding quality or disbond will decrease the structure strength, leading to potential failure. To realize an in situ detection of adhesive joint, flexible piezoelectric comb films are embedded into the adhesive layer to excite and receive ultrasonic guided waves, from which disbond-related indicator is extracted. First, a semi-analytical finite element method (SAFE) is adopted to analyze wave propagation guided by the adhesive joint, and then the interaction of wave with disbond is obtained with a hybrid SAFE and normal mode expansion method. By the hybrid method, when wave is modulated by disbond, wave transmission, reflection, and mode conversion can be quantitatively analyzed, and a relation of delayed wave-arrival-time proportional to disbond length is discovered for wave under a specific mode-frequency combination. Then, to preferably excite this wave, piezoelectric comb films with specific finger width and pitch are designed. Finally, both finite element simulation and experiment are performed, validating the effectiveness of the design for disbond detection.