The　present　research　is　concerned　with　the　free　vibrations　and　energy　transfer　of　a　vibrating　gyroscope,　which　is　composed　of　a　flexible　beam　with　surrounded　piezoelectric　films　in　a　rotating　space.　The　governing　equations　involve　nonlinear　curvature,　and　rotary　inertia　of　an　in-extensional　rotating　piezoelectric　beam　is　obtained　by　using　the　transformation　of　two　Euler　angles　and　the　extended　Hamilton　principle.　The　gyroscopic　effect　due　to　the　rotating　angular　speed　is　investigated　in　the　frame　of　complex　modes　based　on　the　invariant　manifold　method.　The　effects　of　angular　speed,　initial　values,　and　electrical　resistance　to　the　nonlinear　natural　frequencies　of　a　rotating　piezoelectric　beam　are　studied　by　both　linear　and　nonlinear　decoupling　methods.　The　results　reveal　that　the　rotation　causes　one　nonlinear　frequency　to　bifurcate　into　a　pair　of　frequencies:　one　forward　and　one　backward　nonlinear　frequencies.　The　variation　of　the　frequency　with　the　angular　speed　is　used　to　measure　the　angular　speed.　Finally,　the　energy　transfer　due　to　nonlinear　coupling　under　1:　1　internal　resonance　condition　and　the　energy　transfer　due　to　the　linear　gyroscopic　decoupling　are　investigated.