Abstract: Perforated-panel structures have wide potential application under water. But up to now the correlative research is few. The acoustic impedance of underwater perforated-panel is obtained based on the theories for air perforated-panel absorption. Theoretically the sound transmission characteristics of underwater perforated-panel structures are analyzed by the transfer matrix method. The normal incidence sound transmission coefficients are given. The main factors that have effects on the acoustic transmissions are analyzed by simulation, and some important results are obtained. The perforated-panel structures made by ourselves were tested in a standing-wave tube by the four-microphone transfer-function method. The experimental results are approximately in accord with the results obtained by theoretical analysis, which have proved that the theories are correct. This paper has supplied theoretical and experimental bases for the design of underwater perforated-panel structures.