This study aims to examine the mediating effect of political involvement variables on the impact of the presidential debate based upon the political psychology model ,We also set the two groups of students into comparison to explore the instinct influence between Taiwan and Mainland college students by considering the social and political context. It is found that the political knowledge, partisanship, and discussion play significant roles in mediating the effect of the presidential debate. In terms of the mainland group, political knowledge played the most significant part. Those who know less about Taiwan politics are more easily persuasive to the presidential debate. Meanwhile, political discussion and partisanship show their notable impacts on the Taiwan group. For the ones who are lack of political participation or political discussion, they are more easily affected to change their votes since they are more vulnerable to the debate.