Thermo-sensitive copper/paraffin nanocomposites were prepared by high energy ball milling. Fourier transform infrared spectrometer (FTIR), x-ray diffraction (XRD) and transmission electron microscopy (TEM) were used to analyze the composition, phase and microstructure of the composites. Furthermore, their thermal sensitivity was investigated. Results reveal that the phase of composites is mainly composed of copper, paraffin and a small amount of cuprous oxide copper. Nanoparticles homogeneously covered by paraffin form the similar core-shell structure. The mass ratio of copper to paraffin has an obvious influence on the thermal sensitivity.