Because of its good thermal property, nano-graphite (nano-GnPs) materials has became a research hotspots. The best adding amount of polyester type dispersant of dispersed system of nano-GnPsparaffin composite phase change materials (PCMs) was 2% by mechanical and chemical modification methods with nano-GnPs as stuffing. The stable uniform dispersion of composite PCMs was obtained by precipitation and separation. The adding amount of nano-graphene had no effect on the starting and termination points and peak of phase change. However, the adding amount of nano-GnPs will lower the phase change latent heat of composite PCMs in some degree. Phase change latent heat of composite PCMs was 0.7% higher than pure paraffin when the adding amount of nano-GnPs was 1.5%. Moreover, a good stability in the process of circulation with nano-GnPs as stuffing was found in composite PCMs.