Abstract: To enhance the utilization of small-diameter and low-quality wood and promote material conservation and functionalization in building materials, this study fully leveraged longitudinal mechanical strength of wood to construct a novel honeycomb core structure using rubberwood blocks and filled the structure voids with thermal insulation material, addressing the insufficient mechanical performance and single-function limitation of traditional honeycomb sandwich panels. The experiment results show that when the core unit cross-section is square and the porosity is 50%, the honeycomb sandwich panel (PHC) exhibits the optimal flat compressive performance, with a strength of 28.16 MPa and a modulus of 112.96 MPa, representing a 15.7% increase in specific strength compared to rubberwood; after filling with phase change energy storage material, the thermal-insulation honeycomb sandwich panel (PWPCM-PHC) shows a 19.3% reduction in thermal conductivity compared to PHC; during continuous heating, the surface temperature of the PWPCM-PHC remains consistently lower than that of PHC; after 30 minutes of heating, its surface temperature is about 6.1% lower than PHC, indicating a significant enhancement in insulation performance. This material combines light weight, high strength, and excellent thermal insulation, and has excellent prospects for development in the field of building energy savings.