In this study, we use the reactive rf magnetron sputtering method with deposition parameters of RF power of 370W, sputtering pressure of 15 mTorr, substrate temperature of 400¢J, nitrogen concentration (N2/N2+Ar) of 30% and 40%, to deposit highly c-axis orientation AlN thin films on Z-cut LiNbO3 and ST-cut quartz piezoelectric substrate, respectively. The material characteristics of AlN films deposited on Z-cut LiNbO3 and ST-cut quartz substrate with different thickness were obtained by means of the analyses of XRD, SEM and AFM. Besides, the interdigital transducers (IDTs) were fabricated on the bi-layers structure. The AlN film thickness of piezoelectric bi-layers structure was varied in order to discuss its effect on SAW devices and the temperature coefficient of frequency (TCF) of AlN. From the experimental results, it reveals that the center frequency and TCF of SAW filters increase with the increased AlN thin film thickness. Besides it can be concluded that poly-crystalline AlN exhibits a positive temperature coefficient of frequency (TCF).