In　this　paper,　we　propose　an　efficient　method　to　achieve　a　multimode　quantum　Rabi　model　in　a　strong-coupling　cavity　optomechanical　system.　In　the　proposed　proposal,　we　show　that　when　the　driving　bichromatic　laser　is　simultaneously　adjusted　to　red-　and　blue-sideband　excitations,　the　interaction　between　the　cavity　mode　and　the　vibrational　modes　can　be　treated　as　a　multimode　quantum　Rabi　model　under　the　single-photon　strong-coupling　regime.　As　a　typical　example,　we　theoretically　analyze　the　two-mode　quantum　Rabi　model　and　show　that　the　entangled　state　of　two　vibrational　modes　can　be　achieved　in　the　two-mode　quantum　Rabi　model.　Numerical　simulations　confirm　the　validity　of　the　proposed　scheme.