A surface acoustic wave (SAW) device which is made of cBN/diamond composite structures and the fabrication method are disclosed. In the SAW device based on cubic boron nitride and diamond composite structures, the diamond hard layer includes randomly-oriented polycrystalline diamond (poly-D), oriented (heteroepitaxial) diamond, single-crystal diamond wafers and nanocrystalline diamond (nano-D) films. The cBN film with a sound velocity close to that of diamond serves as the piezoelectric layer, which was directly deposited on diamond hard layer without any soft sp.sup.2-BN incubation layer by ion assisted physical vapor deposition (PVD) and plasma-enhanced (or ion assisted) chemical vapor deposition (PECVD). Due to the high sound velocity and the low velocity dispersion between the cBN and diamond layered materials, the present SAW device based on cubic boron nitride and diamond composite structures can improve the device performance and operate at ultra-high frequency range.