Based on the application requirements of auxetic structures in fields such as shipbuilding and aerospace, a novel DRSH (diamond-rhombus shaped honeycomb structure) with in-plane enhanced performance was proposed. The structure was constructed through planar array by introducing combined diamond-rhombus cells into the traditional re-entrant honeycomb. The deformation modes, mechanical properties, and energy absorption characteristics of the DRSH under in-plane loading were systematically investigated by means of a combined approach of quasi-static compression experiments and finite element simulations. The research results indicate that the DRSH exhibits a significant negative Poisson’s ratio effect under various re-entrant angles and wall thicknesses. Its plateau stress and specific energy absorption decrease with an increasing re-entrant angle. Conversely, they improve with an increase in wall thickness. These findings demonstrate that the structural performance can be effectively regulated through geometric parameters. Furthermore, sweep frequency tests were conducted on the DRSH-3D structure. The results show that it possesses stable vibration suppression capability under different excitation amplitudes. Its vibration reduction performance is found to be more significant under conditions of higher excitation amplitudes. This study provides a structural reference for the design and application of negative Poisson’s ratio metamaterials.