Hysteresis current-voltage (Ⅰ-Ⅴ) characteristics are often observed in a highly non-ideal (n ＞ 2) as-deposited nickel (Ni)/4H-SiC Schottky contact.However,we find that this kind of hysteresis effect also exists in an as-deposited Ni/n-type 4H-SiC Schottky structure even if the ideality factor (n) is less than 1.2.The hysteresis Ⅰ-Ⅴ characteristics is studied in detail in this paper by using the various measurements including the hysteresis Ⅰ-Ⅴ,sequential Ⅰ-Ⅴ sweeping,cycle Ⅰ-Ⅴ,constant reverse voltage stress (CRVS).The results show that the hysteresis Ⅰ-Ⅴ characteristics are strongly dependent on the sweeping voltage and post-deposition annealing (PDA).The high temperature PDA (800 ℃) can completely eliminate this hysteresis.Meanwhile,the magnitude of the hysteresis effect is shown to decrease in the sequential Ⅰ-Ⅴ sweeping measurement,which is attributed to the fact that the electrons tunnel from the 4H-SiC to the localized states at the Ni/ntype 4H-SiC interface.It is found that the application of the reverse bias stress has little effect on the emission of those trapped electrons.And a fraction of the trapped electrons will be gradually released with the time under the condition of air and with no bias.The possible physical charging mechanism of the interface traps is discussed on the basis of the experimental findings.