AE technique was applied to the structural strength tests of the ablative composite liner bonded on steel nozzle to figure out the unexpected problem that happened during the flight test. Two different kinds of specimen, which were specimens with some initial crack and without initial crack each, were used for the test. AE test methodology and parameters were investigated to assess the damage of them. NDT using X-ray technique was performed to improve the test reliability before and after each test. The study revealed that AE technique is a good method to evaluate damage on this kind of specimen with better accuracy.