Safavid kings not only compete against poetry and literature, but also, they were promoters and supporters of poets too. The evidence of this assertion is the Shahnameh, which had well-maintained its historical value during Safavid period as well. In this study, we have tried to answer the question why and for what reasons, Shahnameh was important to the Safavid kings by using the method of analysis and description and relying on the study of library sources? Accordingly, the findings of the study it is clear that the person of Shah Ismail I considered this noble work along with the Shiite religion as the second cohesive factor of the Iranian peoples; Because Shah Ismail I and his inheritors, first of all, considered themselves Iranians; They knew the descendants of the kings of ancient Iran and their successors and considered the Shahnameh as their identical document; Secondly, they were aware of the historical role of the Shahnameh in stabilizing the harmony of Iran throughout history, along with the Shiite religion, among the Shiite Iranians; Third, in the war against the Ottomans and the Uzbeks, the poems of the Shahnameh were recycled as a motivating dynamic for the Iranian soldiers. Therefore, they tried to spread the Shahnameh and appreciated it.