This paper describes a theoretical study of the diffraction of Bleustein‐Gulyaev waves at surface imperfections. With the use of the integral representations of the shear‐horizontal waves in a semi‐infinite piezoelectric material, simultaneous integral equations are obtained. Moment methods are applied in order to solve these equations. To obtain a qualitative idea of the propagation characteristic of Bleustein‐Gulyaev waves at surface imperfections, numerical illustrations of the power transmission coefficient, power reflection coefficient, and the scattering power coefficient are shown.