Highly c-axis oriented ZnO films with uniform grains,smooth surface,less defects and high resistance are necessary for high-performance surface acoustic wave(SAW) devices.In this paper,ZnO thin films were deposited on Si(100) substrates and Ti/Si(100) substrates respectively,and the effects of Ti buffer layer on the structure and defect of the ZnO films are discussed.The microstructure,surface roughness,defect and electrical properties of the ZnO films are characterized by X-ray diffraction(XRD),atomic force microscopy(AFM),photoluminescence(PL) spectroscopy and Four-point probe instrument.The results reveal that the ZnO thin film with Ti buffer layer grown at 350 ℃ exhibits strong c-axis orientation,low root-mean square(RMS) roughness,less defects and high resistivity.This work is of great importance for the defect analysis of piezoelectric films and the development of high-performance ZnO SAW devices.