<p>In this paper, a vibro-acoustic modeling method is developed for built-up laminated plate-cavity coupled system based on a unified modified Ritz method. Using the first-order shear deformation theory, the energy equations of the laminated plate are derived and the potential energy functions for the coupling between the neighboring plates are achieved according to artificial spring method. Helmholtz equation is employed to formulate the energy functions for the closed acoustic cavity. Then, the fluid–structure interactions are incorporated by the work due to the acoustic pressure acted on plates and displacement continuity at the interfaces. To satisfy the complex coupling interface restricts, an improved Fourier series is introduced as the unified basis functions for both the displacements of the built-up plates and acoustic pressures of the cavity. Based on the Hamilton’s principle, the vibro-acoustic model for the built-up laminated plate-cavity coupled system is established. Free and forced vibro-acoustic properties of the coupled system are studied. Both mechanical and acoustic loads are considered. The convergence, accuracy and efficiency of the developed method are demonstrated by comparing the results with finite element analysis. The influences of vibro-acoustic coupling on the modal and forced vibro-acoustic properties are then examined.</p>