Abstract: In this paper,a series of ZnO layers with various thicknesses were deposited on heavily doped n-type silicon（100） wafer by DC magnetron sputtering and a set of masks.An Au coated probe and the ZnO/n⁺-Si form a series of Au/ZnO/n⁺-Si structured varistors each with a different ZnO layer thickness.The microstructure of the ZnO films was studied by X-ray diffraction（XRD）,which indicates that ZnO thin films have good crystalline quality with strong c-axis（0002） orientation.UV-Vis transmission spectrum was employed to calibrate the deposition rate of ZnO thin film.Then the I-V curves of the Au/ZnO/n⁺-Si were measured,and threshold voltages of the Au/ZnO/ n +-Si structure with various thickness of ZnO layer were deduced.The results show that the threshold voltage of the Au/ZnO/ n +-Si structure increases linearly as the thickness of the ZnO layer increases.Therefore,it’s possible to finely tune the threshold voltages of thin film varistors.