The present study used the experimental patterns of Go/No Go and no motion contingent negative variation (CNV) task into the research in order to study whether the CNV can express the implication of expectation. Through comparing the CNV under different conditions, the data collected from experiment showed that the key to evoked CNV was close to the warning signal and command signal. Whether the command signal was related to the task would impact on the amplitude of the CNV. This characteristics responses to the subjects' expectation. On this basis, CNV can be used as the electrophysiological index for the reflection of expected value in the conditions of this experiment.