Aluminum nitride (AlN) thin films were prepared by reactive magnetron sputtering on silicon substrate with AlN nano seed crystals in argon and nitrogen gas mixtures. The influences of the deposition parameters (pressure, ratio of argon to nitrogen, sputtering power) on the transmittance and structure of the AlN thin films were investigated. X-ray diffraction (XRD) analysis showed a preferred orientation of the AlN (100). The results also showed the optimal condition for AlN growth, i.e. 0.6 Pa for working pressure, 4:1 for nitrogen/argon ratio and 300W for sputtering power. Since copper could not be adhesive to AlN for heat-sink applications, titanium layer was inserted between AlN and copper as a transition layer to achieve the metallization of AlN. We found that the films with titanium layer had obviously better adhesion property, as compared with the films without titanium layer.