The　experimental　results　of　the　nonlinear　nonplanar　periodic　and　chaotic　vibrations　are　demonstrated　for　a　cantilever　beam　with　square　cross-section　under　harmonic　vertical　base　excitation.　It　is　illustrated　that　this　simple　system　can　exhibit　complicated　dynamics,　including　periodic　doubling　bifurcation　and　chaotic　motion.　The　experimental　results　also　indicate　that　there　indeed　exist　the　multi-pulse　Shilnikov　type　chaotic　motions　for　the　nonlinear　nonplanar　oscillations　of　the　cantilever　beam　in　three-dimensional　phase　space.　It　is　verified　that　the　phenomena　of　the　multi-pulse　Shilnikov　type　jumping　orbits　detected　by　the　theoretical　analysis　indeed　exist　in　the　nonplanar　nonlinear　motion　of　the　cantilever　beam　subjected　to　a　harmonic　vertical　base　excitation　at　the　fixed　end.　Copyright　©　2007　by　ASME.