Abstract: The structural acoustic radiation loss factor and radiation efficiency of a plate under fluid loading were computerized and analyzed using finite element method and Rayleigh integral coupled method.The finite element method was employed for discretizing the structure.The Rayleigh integral was used for modeling the acoustic fluid.The modal acoustic radiation loss factor and the modal acoustic radiation efficiency were obtained with fluid-loaded undamped normal modes and reduced order models respectively.The numerical results of a plate in the air and in the water show that the acoustic radiation loss factor of an odd-odd mode is far larger than other types of modes,and the acoustic radiation loss factor in the air is about one order of magnitude lower than that in the water.The acoustic radiation loss factor in water is much bigger than the structural loss fa ctor,and the acoustic radiation loss factor in the air is on the same order of magnitude of the structural loss factor.The acoustic radiation efficiency in air is about two orders of magnitude higher than that in water .