The uniaxial tensile test method of micro nanocomposited ceramics is put forward under ultrasonic excitation. Based on nonlocal theory,fracture mechanism,microstructure and mechanical properties of micro nanocomposited ceramics are studied through the experimental study of material properties under ultrasonic vibration tensile test,and the effects of ultrasonic frequency on the axial tensile stress and nonlocal decay rate are obtained.The results of experiments show that tensile stress is attenuated when the tensile of the specimen is in the ultrasonic vibration frequency ranges and this attenuation phenomenon becomes more and more evident by the increase of the ultrasonic frequencies.Microscopical analysis of tensile fracture is conducted. It shows that ultrasonic vibration changes the fracture mode and microstructure and improves the toughness of the material,and it says that it is much easier to achieve ductile mode machining under ultrasonic excitation. The results of experiments are in accordance with the analysis of nonlocal theory.