Abstract: To research the application of Laser Shearography in testing bonding quality of the interface between grain and liner, main principle and course of Nondestructive Testing(NDT) were analyzed. According to experiment and testing of different grains, some improvement measure are given to solve the existing problems and improve efficiency. The debonding-area diameter >3 mm could be detected by the improved system. It can be used to test the quality of free-loading grain in production and using course.