This　paper　presents　the　analysis　of　the　global　bifurcations　and　chaotic　dynamics　for　the　nonlinear　nonplanar　oscillations　of　a　cantilever　beam　subjected　to　a　harmonic　axial　excitation　and　transverse　excitations　at　the　free　end.　The　governing　nonlinear　equations　of　nonplanar　motion　with　parametric　and　external　excitations　are　obtained.　The　Galerkin　procedure　is　applied　to　the　partial　differential　governing　equation　to　obtain　a　two-degree-of-freedom　nonlinear　system　with　parametric　and　forcing　excitations.　The　resonant　case　considered　here　is　2:1　internal　resonance,　principal　parametric　resonance-1/2　subharmonic　resonance　for　the　in-plane　mode　and　fundamental　parametric　resonance-primary　resonance　for　the　out-of-plane　mode.　The　parametrically　and　externally　excited　system　is　transformed　to　the　averaged　equations　by　using　the　method　of　multiple　scales.　From　the　averaged　equation　obtained　here,　the　theory　of　normal　form　is　applied　to　find　the　explicit　formulas　of　normal　forms　associated　with　a　double　zero　and　a　pair　of　pure　imaginary　eigenvalues.　Based　on　the　normal　form　obtained　above,　a　global　perturbation　method　is　utilized　to　analyze　the　global　bifurcations　and　chaotic　dynamics　in　the　nonlinear　nonplanar　oscillations　of　the　cantilever　beam.　The　global　bifurcation　analysis　indicates　that　there　exist　the　heteroclinic　bifurcations　and　the　Silnikov　type　single-pulse　homoclinic　orbit　in　the　averaged　equation　for　the　nonlinear　nonplanar　oscillations　of　the　cantilever　beam.　These　results　show　that　the　chaotic　motions　can　occur　in　the　nonlinear　nonplanar　oscillations　of　the　cantilever　beam.　Numerical　simulations　verify　the　analytical　predictions.