The　nonlinear　dynamic　characteristics　of　a　flexible　beam-ring　structure　under　fundamental　harmonic　excitation　are　systematically　investigated.　The　nonlinear　partial　differential　governing　equations　of　motion　for　the　beam-ring　structure　are　derived　by　using　Hamilton＇s　principle　and　discretized　into　two　coupled　ordinary　differential　equations　including　quadratic　and　cubic　nonlinearities　by　Galerkin＇s　technique.　The　potential　internal　resonance　relationship　of　the　beam-ring　structure　is　recognized　through　analyzing　the　mode　shapes　and　linear　frequencies.　The　method　of　multiple　scales　is　utilized　to　approximately　analyze　the　dynamic　system　and　yield　a　set　of　autonomous　equations　under　the　case　of　1:1　internal　resonance　and　a　primary　resonance.　The　amplitude-frequency　characteristics　and　the　stability　of　the　steady-state　responses　are　studied　numerically.　The　frequency-response　curves　show　that　some　parameters　of　the　amplitude-frequency　equations　have　significant　contributions　to　the　nonlinear　responses　near　resonance　of　the　beam-ring　structure.　Finally,　the　bifurcation　diagram　is　obtained　and　the　Poincare　map,　power　spectra　and　the　largest　Lyapunov　exponent　are　used　to　identify　the　nonlinear　dynamic　behaviors　of　the　beam-ring　structure.　From　the　numerical　simulations,　it　is　found　that　there　exist　typical　nonlinear　phenomena　such　as　multi-value　solutions,　jumps,　bifurcations,　multiple　periodic　and　chaotic　motions　in　the　beam-ring　system.　This　work　also　proposes　a　reference　for　nonlinear　modeling　and　dynamic　analysis　of　similar　complex　structures.　©　2023