To investigate the influence of geometric parameters on the band-gap characteristics of periodic wave barrier blocks, this study analyzes a periodic barrier structure based on phononic crystal band-gap theory. Using the finite element method, a periodic wave barrier block composed of a concrete matrix, a rubber coating layer, and a natural soil core is modeled to evaluate its band-gap characteristics. Orthogonal experiments are subsequently designed to analyze the effects of geometric parameters on the complete band gap, and indoor model experiments are conducted to verify the effectiveness of the proposed barrier structure.Results show that the lattice constant, coating layer thickness, and core size significantly affect the band-gap width, whereas the influence of core shape is relatively insignificant. The main factors affecting the band-gap characteristics, in descending order of influence, are: lattice constant, core size, coating layer thickness, and core shape. The experimentally observed attenuation zones agree well with the theoretically predicted complete band-gap ranges, thereby confirming the band-gap characteristics of the periodic wave barrier blocks.