The piezoelectric AlN thin films were prepared using middle frequency(MF,40 kHz) magnetron reactive sputtering process with dual s-gun structure. The electrode Mo thin films were made using DC magnetron sputtering process. The Au / Cr bottom electrode films and Al/Cr top electrode films were prepared by using pulse DC magnetron sputtering process to sputter gold (Au), chromium (Cr), aluminum (Al) targets. The AlN, Mo and Au thin films were analyzed by X-ray diffraction(XRD). The results show that the (002) crystal surface of the composite aluminum nitride AlN piezoelectric film, the (110) surface of Mo film and the (111) surface of Au film have excellent preferred orientations, indicating that the Al/Cr/AlN/Au/Cr/YAG composite piezoelectric film can be used to develop Ku-band and K-band bulk acoustic wave microwave delay lines (BAWDL), and the insertion losses are as low as 43.7 dB and 54.6 dB, respectively.