The aim of this paper is to study and solve the disadvantage of standing wave on the damage detection by ultrasonic thermal wave testing technology. The vibration characteristics and acoustic chaos phenomena of the structure under ultrasonic excitation were numerically analyzed. Firstly, by establishing a composites finite model with a crack, the resonance models of the structure under different excitation frequencies were analyzed. It is found that the harmonic wave response of the structure under harmonic ultrasonic wave with the response frequency was equals to the excitation frequency, and the standing wave easily appeared. Then, by improving the composites finite model, the influences on the testing result caused by acoustic chaos were analyzed. The numerical results show that, under the same excitation frequency, the standing wave was effectively eliminated by acoustic chaos. Acoustic chaos is beneficial to the detection by increasing the surface temperature difference at the damage, and the probability of acoustic chaos generated is increased by increasing the excitation frequency. And the detection capability and conditions can be improved according to this result.