Abstract: There has been a sharp contradiction between dynamic political action with openness and closed legal institution without adaptation from ancient Greek, where life of action and life of meditation started to distinct themselves from each other.For Arendt, the question about the relationship between political action and legal institution is very important since it not only involves with the maintenance of the present political order, but also relates to the realization of human public freedom.As an ancient contradiction, the intense relationship between political actions and legal institution shows itself as the constraint legal institution puts on political action and the anti-constraint from political action.Contrary to the contempt toward political action from the tradition of western political philosophy, Arendt revived the basis of real politics, revealed the relationship between political action and legal institution, and realized the political dream in which the strain between these two powers had been dissolved and human freedom had been realized in the "Institutionalizing the revolutionary spirit" political institution comprehensively.