In order to investigate the enhancement effect of the combination of phase-change materials (PCM) with porous media on thermal conductivity, and to explore the realization of the regulation of the thermal conductivity of the composite phase-change system at the microstructural level within the pore scale, the four-parameter random generation method is combined with the lattice Boltzmann method to form a phase change heat transfer framework for simulating the solid-liquid phase change process. Considering changes in pore structure parameters, the effect of anisotropy on the kinetics of the melting process within the cavity is revealed by heating different surfaces of a 3D cavity. It is found that the melting efficiency of PCM in the horizontal heat transfer direction of the pore structure is higher than that in the vertical heating direction. At a porosity of 0.6, the melting time of PCM is reduced by 17.9% under different heating directions. Similarly, a pore radius of 1.5 leads to a 16.5% reduction in melting time across different heating orientations.