Phase change material (PCMs) are increasingly valued for storing and releasing renewable thermal energy, benefiting sustainable domains of energy-efficient construction, electronics, and cold chain logistics, etc. Conventional PCMs often confront formability and mechanical limitations above the melting temperatures of PCMs, hindering their suitability for structural thermal management materials to accommodate intricate geometries. In this work, we developed solvent-responsive wood gels with muscular-inspired adjustable stiffness via in-situ polyvinyl alcohol (PVA) polymerization within delignified basswood. Subsequent immersion in liquid PEG as the representative liquid PCMs yields a mechanically robust wood PEG gel (PEG/PVA/W) with stable shape and form. PEG serves dually as a PCM and poor solvent, facilitating phase separation and robust hydrogen bonding. The fabricated wood composite showcases impressive mechanical properties (80.9 MPa stress, 4.8 GPa modulus) and adjusts 2D and 3D shapes, which is 530 times higher than PVA/PEG hydrogel and is versatility for intricate structural thermal management applications. Moreover, life cycle assessments unveil significantly reduced environmental impact compared to conventional plastics, positioning it as an optimal choice for energy-efficient buildings, cold chain transportation, and thermal insulation packaging materials.