This paper is concerned with the development of Trefftz p-element for twodimentional piezoelectric materials. Solutions in Stroh formalism for transversely isotropic piezoelectric materials are used for the intra-element displacement and electric potential (DEP) fields together with an independent DEP frame function field along element boundaries. The formulation is based on a modified variational functional in which electric field and strain are taken as basic variables. The final unknowns are the parameters of the frame function field consisting of the usual degrees of freedom (DOF) at corner nodes and an optional number of hierarchic DOF associated with the mid-side nodes. Some numerical examples are considered to show the application of the proposed formulation.