The results of existing studies showed that positive emotions sped from the cardiovascular aftereffects of negative emotions. But the existing studies provided evidences not enough for this recovery effects. Especially, what is the mechanism of autonomic nervous activity for the recovery effects? Few studdies focused on it. So this study aims to reexamine the effects that positive emotions speed from the cardiovascular sequelae of negative emotions and explore the mechanism of the autonomic nervous acitivity underlying it. In the experiment, after 180 seconds baseline period, participants were asked to view an emotionally evocative film that induced fear, immediately following fear arousal, participants were randomly assigned to view an emotionally evocative videoes that induced amusement, sadness, or neutrality for 120 seconds, then kept relaxing state for 120 seconds. 96 participants recruited from college students attended the experiment. The results of experiment indicated that: compared to participants who viewed the neutral and sad secondary videoes, those who viewed the positive film exhibited more rapid returns to pre-film levels of cardiovascular activation. Moreover, compared to participants who viewed the neutral and sad secondary videoes, those who viewed the positive film exhibited stronger vagal activation in recovery periods. Positve emotion sped recovery from cardiovascular response of negative emotions, and the mechanism of the autonomic nervous acitivity underlying it was that stronger vagal activation was generated in the state of positive emotion.