A parallel iterative partitioned coupling analysis system for large-scale acoustic fluid-structure interactions. The authors investigate the acoustic fluid-structure interaction which can change the dynamic characteristics of the structure, and particularly its response to external excitation parameters such as seismic loading. Using iterative partitioned coupling techniques, the authors examine here large-scale acoustic fluid-structure interaction problems. An open-source parallel finite element analysis system called ADVENTURE is used. This system adopts an efficient preconditioned iterative linear algebraic solver. A parallel coupling tool called ADVENTURE_Coupler is developed to efficiently handle interface variables in various parallel computing environments. The authors also use the Broyden method for updating interface variables to attain robust and fast convergence of fixed-point iterations. Some tests are performed to validate the algorithm. The system runs efficiently in a parallel environment, and it is capable of analyzing three-dimensional complex-shaped structures with more than 20 million degrees of freedom. The numerical results also show good agreement with experimental data.