This paper presents a research on the attenuation of cyclic stress amplitude and the variation of microstructure under the action of ultrasonic vibration in crack propagation for Al2O3-ZrO2 composite nano-ceramics. To interpret this phenomenon, the nonlocal theory is introduced to establish the constitutive model under the ultrasonic condition based on the specified 2D attenuating function. The mechanics behavior of the ceramics under the action of ultrasonic vibration is analyzed according to the relationship between the internal character length and the external character length (i.e. ultrasonic wave length). In addition, the variation law of the cyclic stress amplitude and microstructure with different ultrasonic frequencies is also studied in this paper. It is shown that the cyclic stress amplitude is attenuated under the action of ultrasonic vibration, and this attenuation phenomenon becomes more and more evident by increasing the ultrasonic frequency. The results of experiment are in accordance with the theoretical conclusions drawn from the nonlocal theory, which verifies that the action of ultrasonic vibration can actually accelerate the ceramic crack propagation.