Abstract: Background: Considerable studies have shown that intentionally altering responses to unpleasant stimuli affects physiological and hemodynamic activity associated with emotional and cognitive processing. There are two commonly used emotion regulation strategies: cognitive reappraisal and expressive suppression, which can reduce our subjective emotion experience and hemodynamic activity. However, there are few researches about the temporal characteristics of these two emotion regulation strategies. Based on pervious reports, t he present study hypothesized that there would be significantly decreased electrophysiological activity during cognitive reappraisal and expressive suppression emotional responses beginning around 400 ms post stimulus and lasting several hundred milliseconds. Methods: In the present experiment, we measured the late-positive potential (LPP) of the visually evoked event-related brain potential to examine the effects and the differences of the two emotion regulation strategies. Fourteen participants received instructions to view, reappraise, and suppress the emotional responses to fearful stimuli. All stimuli were emotionally evocative scenes taken from Chinese affective picture system, and appraised before. Results:(1)In the terms of amplitude, comparing instructions to view, the amplitude of the LPP was decreased during instructions to cognitive reappraise and the differences were significant, while the amplitude of the LPP was decreased during instruction to expressive suppression but the differences were not significant. (2)In the terms of temporal part , the differences between instructions to cognitive reappraise and view occurred at 400ms and last to more than 600ms, while the differences between instruction to expressive suppression and view occurred at 450ms and only last to 550ms. Conclusions: the present study displayed that these two emotion regulation strategies can modulate our emotional responses. But the effect of cognitive reappraisal was earlier and more lasting than expressive suppression. These results were evidences to that cognitive reappraisal is more effective than expressive suppression, and is better for people’s physical and mental health. Key words: emotion regulation; cognitive reappraisal; expressive suppression; LPP