Abstract: Thermal wave technique(TWT) has gained broad application attributed to the advantages of such as high speed, non-contact and can achieving on-line inspection capability, etc. In this paper, TWT was used to detect the disbond defect between shell and heat-insulating layer of Solid Missile Motor(SMM) for nondestructive inspection. Numerical simulation method was used to investigate the process of TWT and the effect of defect size on the testing sensitivity was further studied, which was verified by experiment. The results of the simulation and experiment show that the TWT has a high speed of detecting the disbond defect, which could ascertain the defect position exactly and achieve quantitative testing for the defects. Moreover, the bigger of the defect, the easier be detected. An un-known defect may be caused by manufacture techniques was found out by the experiment, which indicated that thermal wave technique could also inspect and evaluate the quality of adhesive interface.