In this paper, a single-phase quadrangular star-shaped ligamentous heterostructure is constructed, and a two-phase structure is formed by attaching a resonator at the center of the structure. The lattice theory and finite element modeling are combined to analyze the band structure of the two structures, and the additional resonator at the center of the structure improves the bandgap range. Based on this, the bandgap can be widened and reduced by adjusting the resonator size. In the structural vibration modal analysis, it is explained that the coupling of traveling wave and vibration can open the omnidirectional bandgap, which provides guidance for the subsequent structural optimization. In addition, the relationship between bandgap opening and directional propagation of elastic waves is verified by a comprehensive analysis of group velocity, phase velocity, and other means. Finally, the transmission characteristics and stress distribution of the structure within the finite period structure are investigated, and it is further verified that the structure has a strong attenuation capability to vibration. This structure has good vibration isolation capability in a wide frequency range and has potential for application in complex vibration control.