Abstract: The stability of the particle in Acoustic levitation apparatus is discussed according to the results of the numerical simulation. It has found that with the increase of the Sound Pressure Level (SPL) of sound source, the deformation of the wave form of sound pressure is enhanced and the influence of higher harmonics is strengthened. The distributions of harmonics are also affected by the change of the chamber length. With the increase of the SPL, the nodes of sound pressure move Periodically, and sound radiation pressure near the nodes increases obviously, while sound radiation pressures are almost equal to zero in the loWer SPL region.