The tragedy of Prince Siyavash is one of the four tragic stories in the Iranian national epic,Shahnameh.This tragedy in Shahnameh integrates the basic plots of this story in historical texts and folklore,but in the process of creating the national epic,Ferdowsi also carried out a series of ingenious rewriting in order to serve the needs of building national identity.The perfect fusion of tragedy and epic renders the magnificence of the fate of the Iranian nation and inspires the sense of national belonging of the Iranian people.Based on Shahnameh and other related Persian documents,this paper will sort out the myths and legends before Shahnameh and the prototypes of the Siyavash story in historical documents,explore the poet's rewriting and reshaping of these prototypes,and discuss the role of national identity construction played by the Siyavash tragedy from three perspectives of character shaping,plot design and epic writing.