The addition of metal skeletons to form a composite phase change material (PCM) has an important effect on the solidification process. In this paper, an experiment was conducted to research the effect of gradient metal skeletons on the solidification characteristics of phase change materials. By constructing a solid-liquid phase change visualization experiment bench, the basic performance of the solidification processes of pure PCM and PCM with a metal skeleton was observed independently, and the features of the internal temperature variation of PCM were discovered with accurate temperature measurement. It was found that heat conduction and natural convection were the main heat transfer modes in the solidification process of PCM, and natural convection bent the bottom of the solid-liquid phase change interface to the right during solidification. However, natural convection has less effect on the solidification process of composite PCM. The embedded metal skeleton improved the temperature uniformity inside the PCM and increased significantly the solidification rate. Better solidification characteristics in composite PCM with X-positive direction gradient porosity skeleton result in a shorter solidification time overall and faster cooling. Meanwhile, it was found a complex local thermal non-equilibrium effect between the metal skeleton and PCM during solidification. The thermally non-equilibrium effect of the paraffin and skeleton is visible during solidification as two peaks and two valleys. At the end of the paraffin phase change, the local thermal non-equilibrium impact becomes most noticeable.