Blue Mosque is one of the works by Abul Mozaffar Jahanshah bin Qara Yousef, a member of Qaraqoyounlu tribe, in Tabriz. It was completed in 870 AH under Jan Beigum Khatoon's supervision (Jahanshah's wife).This mosque consists of diverse patterns including herbal and geometric ones as well as various epigraphs. Epigraphs which are mostly recorded by Kufic and Thulth scripts are in accordance with adjacent patterns to show moderation and harmony. The main objective of this research was to determine the effect of Mysticism and Sufism, including Hurufiye faction on epigraphs' content. The method employed in this paper was both descriptive and analytical. In line with this, data were collected through library research method and visiting the monument. Research findings showed that the greatest diversity of colors are specified to azure blue in epigraphs and white in epigraphs' script which are symbolic in community of the mystics. Moreover, sun and star patterns as well as Arabic logion are clearly revealed the impact of Mysticism and Sufism in creating ornaments of this great building during Qaraqoyounlu's age. Last but not the least, this paper showed that religious evolutions such as the existence of Hurufiye faction's beliefs along with Mysticism and Sufism had significant impact on the formation of patterns and epigraphs' contents of the building.