The band structure and transmission characteristics of a new two-dimensional (2D) piezoelectric phononic crystal plate consisting of four epoxy short plates periodically connected with a square lattice of a prismatic piezoelectric material coated with plexiglass are investigated by supercell method and finite element method. By changing the electric boundary conditions imposed on the upper and lower surfaces of piezoelectric scatterers, a point defect waveguide with adjustable paths is formed, which overcomes the limitation of immutability in the direction of the vibration waveguide, with material and structural parameters fixed. Then the controlling of the piezoelectric effect can change the material parameters of piezoelectric components in phononic crystals, showing that the piezoelectric constants have a great influence on the complete bandgap, which is beneficial to the formation of defect states; when the frequency of the defect state appears in the band gap, the frequency-responding range of the defect state expands. The analysis of the displacement vector field indicates that the strain energy in the resonance of the new structure is almost completely limited to the upper and lower surfaces of the central piezoelectric scatterer. We use the recycling circuit to connect the electrodes on the upper and lower surfaces of the piezoelectric sheet. At this time, the output electrical energy can supply the power to the DC load, and the mechanical energy of vibration can be converted into electrical energy. The results of this work provide a reference for the self-powered technology of waveguide and wireless sensor device with adjustable path.