Nano-aluminum, which has high thermal conductivity and good compatibility, was added into paraffin to improve its thermal conductivity. Surface modified technology was adopted and dispersant was used to prepare uniform and stable organic phase-change nano-fluid of paraffin and nano-aluminum. Experiments were conducted to test the phase-change temperature and latent heat of the prepared organic phase-change nano-fluid. Results show that the addition of nano-aluminum has no effect on phase-change temperature, but it changes phase-change latent heat of the prepared organic phase-change nano-fluid. Reduced degree of the latent heat is nearly proportional to the quantity of the added nano-aluminum.