Wood-plastic composites, as green eco-materials, are widely used in the field of home and building materials, but with a single function. Phase-change heat storage materials can store or release heat through a physical phase transition to achieve energy savings and emission reduction. In this paper, plant fibers are used as the matrix, which is introduced into wood-plastic composites to construct a function/structure-integrated shaped phase change heat storage wood-plastic composites and endow the wood-plastic composites with the function of storing and releasing heat. The performance of wood-plastic composites is examined using image recognition and X-ray imaging. Simulating and analyzing the thermoregulatory and energy-saving functions of phase change wood-plastic composites in the building heating environment was done by establishing a heat transfer model. Finally, the material was visualized and applied to the interior decoration. The results show that the apparent density of the wood-plastic composite material is 1.15 g/cm3, the tensile property is 42.8 MPa, the flexural modulus is 2455 MPa, and its comprehensive physical and mechanical properties are better than those of the solid wood core when the amount of plant fiber added is 40 phr. At the same time, the thermal conductivity of this material is improved by 7.74% compared with the traditional solid wood core, which shows good energy saving and temperature regulation effects and possesses the potential of energy saving when applied in interior decoration.