Abstract: Abstract: A question was studied primary on propagation of elastic waves through a contact interface between two piezoelectric solids. When the incident wave is strong enough, the contact interface will separate or slip in local interface areas, the extent and location of the separation and slip regions will vary with the external mechanical-electrical loads and the incedent wave. The solution of the slip regions are given theoretically by using Fourier analysis and Matlab software, and a method is developed to determine the condition that the separation、slip and stick region will be generated, and more the factor influencing the slip and sepration location are analyzed through an example.