As the phase change material (PCM), pure paraffin wax is mixed with CuO (high heat conduction) and Span-80 (as a dispersant) in this research. The CuO/paraffin nanocomposite PCMs is synthesized with mass fractions of 0.3%, 0.6%, 0.9% and 1.2% by a two-step method. Dispersion stability and nanoparticle morphology of CuO/ paraffin nanocomposite PCMs are analyzed by using a spectrophotometer and a scanning electron microscopy. Thermal conductivity and phase change latent heat of CuO/paraffin nanocomposite PCMs are investigated by changing the nanoparticle mass fraction. In addition, this paper investigates heat transfer characteristics of the heat pipe-PCMs module and effects of fan power and heating power on the performance of the cooling module. Results show that the thermal conductivity of the PCMs increases by 24.4% when 1.2% CuO nanoparticles are added into the paraffin, whereas the latent heat of phase change decreases by 1.5%. Compared to without PCMs, the heat pipe with 1.2% CuO/paraffin composite at 10 V fan voltage shows 17.2% reduction of the evaporator temperature. In addition, it is found that both a high fan voltage and a high mass fraction of CuO nanoparticles can significantly improve the heat transfer characteristics of the evaporation.