In　this　paper,　cantilevered　beam　with　piezoelectric　layers　are　considered　as　the　mechanical　model　of　vibration　energy　harvesters.　This　paper　aims　to　investigate　the　complicated　dynamics　behavior　of　the　nonlinear　vibrations　of　the　cantilevered　piezoelectric　beam.　The　base　excitation　on　the　harvester　beam　is　assumed　to　be　harmonic　load.　Based　on　the　third-order　shear　deformation　theory　and　the　Hamilton＇s　principle,　the　nonlinear　equations　of　motion　for　the　cantilevered　piezoelectric　beam　are　derived.　The　Galerkin＇s　approach　is　employed　to　discretize　the　partial　differential　equations　to　the　ordinary　differential　equations　with　one-degree-of-freedom.　The　method　of　multiple　scales　is　used　to　obtain　the　averaged　equations　in　the　polar　form.　Based　on　the　actual　work　situation　of　the　cantilevered　piezoelectric　beam,　it　is　known　that　the　base　excitation　plays　an　important　role　in　the　nonlinear　vibration　of　the　cantilevered　piezoelectric　beam.　From　the　averaged　equations　obtained,　numerical　simulations　are　presented　to　investigate　the　effects　of　parameters　on　the　steady-state　responses　of　the　cantilevered　piezoelectric　beam.　We　analyze　the　influences　of　the　excitation　magnitude,　the　excitation　frequency,　the　piezoelectric　material　parameter　and　the　damping　parameter　on　the　steady-state　responses　of　the　cantilevered　piezoelectric　beam.　In　addition,　it　is　observed.　that　the　base　excitation　has　significant　influence　on　the　nonlinear　dynamical　behavior　of　the　cantilevered　piezoelectric　beam.