A method of composite Eshelby inclusion is proposed for aferroelectric grain with domain switching embedded in a polycrystalline ferroelectric matrix. The method quantifies the twinning structure due to spontaneous polarization, as well as the conventional and non-conventional domain structures after poling induced domain reorientation of 90 degree. The predicted parameters include the volume fraction, the thickness, and the surface inclination angle of switched domain plates. The domain wall energy for non-conventional domain structures is derived in terms of the arrays of misfit dislocations. The domain geometries predicted by the present work agree with the measured domain morphology near an indentation crack tip when subjected to lateral electric field.