AlN piezoelectric thin films were prepared by DC magnetron reactive sputtering. A good c-axis orientation is essential for obtaining high piezoelectric coefficients. Therefore, the experiments were designed about the four parameters of the sputtering power, volume ratio of N2 and Ar, gas pressure, and substrate temperature, in order to make sure the deposition parameters of the c-axis orientation AlN film. The crystal structure and full width at half maximum (FWHM) of the thin films were analyzed by X-ray diffraction (XRD). The results show that the optimal process parameters were the sputtering power of 200 W, volume ratio of N2 and Ar of 2 : 8, gas pressure of 3.75 mT. The results provide the experiment evidence and process base for the next study.