The gating of ion channels has widely been modeled by assuming the transition between open and closed states is a memoryless process. Nevertheless, the statistical analysis of an ionic current signal recorded from voltage dependence K+ single channel is presented. Calculating the sample autocorrelation function of the ionic current based on the digitized signals, rather than the sequence of open and closed states durations time. The result is shown existence memory. For difference voltage, the ion channel current fluctuation has difference correlation attributions. The result suggests the correlation character of the ionic current fluctuations. Also the possible biological implication of the findings have been discussed.